Methods and systems for recovering terpene compositions from wood drying exhaust

ABSTRACT

Methods and systems for recovering terpenes and controlling the composition of terpenes collected from wood drying processes are provided. In particular, a sorbent having adsorbed materials, including terpenes, from a wood drying process can be desorbed in a desorber, resulting in a gaseous stream containing terpenes, which can be condensed and collected from the gaseous stream. The conditions of desorption can be controlled to ensure a desirable amount of alpha-pinene and beta-pinene relative to other terpenes, such as dipentene and camphene, in the collected terpenes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase application based onPCT/US2019/015729, filed Jan. 29, 2019, which claims priority to U.S.Provisional Application No. 62/623,192, filed on Jan. 29, 2018; U.S.Provisional Application No. 62/623,204, filed on Jan. 29, 2018; and U.S.Provisional Application No. 62/623,211, filed on Jan. 29, 2018, thecontents of which are hereby incorporated by reference herein in theirentireties.

1. FIELD OF THE INVENTION

Methods and systems for recovering and controlling the compositions ofterpenes extracted from exhaust streams are provided. The presentdisclosure provides various treatments that can be applied to processexhaust streams from wood dryers to obtain an exhaust stream suitablefor downstream recovery of terpenes from the exhaust stream.Additionally, the disclosed methods and systems use a fluidized bedcontaining a sorbent to reduce and/or remove volatile components fromwood drying processes.

2. BACKGROUND OF THE INVENTION

Turpentine is an important raw material in many industries and can beobtained from trees, usually pine trees, or citrus crops, for example bydistilling a resin or extracting the turpentine during the digestion ofwood products. Turpentine can be used as fuel or as a solvent in manyend products, including paints and varnishes. Additionally, turpentine,and constituent components thereof, can be used as a precursor inorganic synthesis to create valuable organic compounds. These compoundsare frequently used as flavors and fragrances in a variety of consumerproducts.

Turpentine contains a mixture of different terpenes, primarilymonoterpenes. Turpentine is particularly valuable for organic synthesisapplications because it contains predominantly higher value terpenes,such as alpha-pinene and beta-pinene. Turpentine also contains lowervalue terpenes, such as dipentene and camphene, but to a lesser degree.Because of the valuable uses for turpentine, it is desirable to createterpene compositions derived from other sources that similarly have highamounts of alpha-pinene and beta-pinene.

Because terpenes are found in wood products, emissions from wood dryingoperations generate exhaust containing such terpenes, which areregulated under emissions standards as volatile organic compounds(VOCs). Wood drying exhaust also contains a number of other regulatedpollutants, including other hazardous air pollutants (HAPs), carbonmonoxide (CO) emissions, carbon dioxide (CO₂) emissions, NO_(x)emissions, and particulate matter. Per regulations applicable to new“major” sources of air pollutants or “major modifications” at existingmajor sources, such pollutants must be controlled using the BestAvailable Control Technology (BACT). Current industry standards requireexhaust from wood drying processes to meet applicable emissionsstandards and/or to be treated with a control device to reduceemissions. The control device most commonly used to reduce HAPs and VOCsfrom wood drying processes is a Regenerative Thermal Oxidizer (RTO),which combusts volatile components from the exhaust stream prior toemission into the atmosphere. Combustion in RTOs is energy intensive,consuming large amounts of fuel and electricity. Combustion also resultsin large amounts of NO_(x) emissions and greenhouse gases, such as CO₂.Moreover, RTOs destroy any VOCs that could otherwise be recovered fromthe wood drying exhaust. It would be advantageous if these VOCs, andspecifically terpenes, could instead be recovered from the wood dryingprocess exhaust.

Thus, there remains a need in the art for methods and systems forrecovering terpenes having a desirable composition from wood dryingoperations. The disclosed subject matter addresses these and otherneeds.

3. SUMMARY

The presently disclosed subject matter provides techniques forrecovering and controlling the composition of terpenes, and inparticular, terpenes collected from exhaust streams from wood dryingprocesses. A sorbent having adsorbed materials, including terpenes, froma wood drying process can be desorbed in a desorber, resulting in agaseous stream containing terpenes. The conditions of desorption can becontrolled to ensure a desirable amount of alpha-pinene and beta-pinenerelative to other terpenes, such as dipentene and camphene, in thecollected terpenes.

Thus, in certain aspects, the present disclosure provides methods ofcontrolling the composition of terpenes collected from a wood dryingprocess that include providing a sorbent having adsorbed materials fromthe wood drying process at a first temperature, heating the sorbent to asecond temperature to release the adsorbed materials into a gaseousstream comprising terpenes, and collecting a terpene stream from thegaseous stream, wherein the terpene stream comprises alpha-pinene and/orbeta-pinene.

In certain embodiments, the terpene stream can include from about 0 wt-%to about 100 wt-% alpha-pinene and from about 0 wt-% to about 50 wt-%beta-pinene. In certain embodiments, the terpene stream can include fromabout 1 wt-% to about 20 wt-% alpha-pinene and from about 0 wt-% toabout 20 wt-% beta-pinene.

In certain embodiments, the method can include maintaining the sorbentat the second temperature for less than about 2 hours. For example, thesorbent can be maintained at the second temperature for from about 30minutes to about 1.5 hours.

In certain embodiments, the second temperature can be less than about450° F. or less than about 430° F. Alternatively, the second temperaturecan range from about 390° F. to about 420° F.

Under such conditions, a terpene stream having enhanced alpha-pineneand/or beta-pinene content can be recovered. For example, as embodiedherein, the terpene stream can include from about 50 wt-% to about 97wt-% of alpha-pinene and beta-pinene combined. The terpene stream cancontain alpha-pinene in amount of from about 20 wt-% to about 97 wt-%.Additionally or alternatively, the terpene stream can includebeta-pinene in an amount of from about 5 wt-% to about 60 wt-%. Incertain embodiments, the terpene stream comprises from about 0 wt-% toabout 20 wt-% of dipentene and/or from about 0 wt-% to about 15 wt-% ofcamphene.

The presently disclosed terpene streams can be sulfur-free. In certainembodiments, the gaseous stream of the present disclosure can furthercomprise nitrogen and/or steam. For example and not limitation, thegaseous stream can comprise at least 95 wt-% nitrogen. Additionally oralternatively, in addition to terpenes, the gaseous stream can include ahazardous air pollutant selected from the group consisting offormaldehyde, methanol, phenol, acrolein, acetaldehyde, propionaldehyde,fatty acids, acetic acid, and combinations thereof. In certainembodiments, the sorbent can comprise activated carbon. Additionally,the desorber can be heated to the second temperature within a desorberincluding one or more packed moving beds. Additionally or alternatively,in certain embodiments, the desorber can include one or more accesspanels, e.g., to provide access to the interior of the desorber duringcleaning and/or maintenance operations. As embodied herein, collectingthe terpene stream from the gaseous stream can include condensing theterpene stream through a cooling system optionally comprising acondenser.

As embodied herein, methods of controlling the composition of terpenescollected from a wood drying process can include providing a sorbenthaving adsorbed materials from the wood drying process at a firsttemperature, heating the sorbent to a second temperature to release theadsorbed materials into a gaseous stream comprising terpenes, andcollecting a terpene stream from the gaseous stream, wherein the terpenestream comprises alpha-pinene and/or beta-pinene. The sorbent can beheated to the second temperature within a desorber comprising one ormore packed moving beds.

In other aspects, the present disclosure provides systems forcontrolling the composition of terpenes collected from a wood dryingprocess. Such systems can include a sorbent at a first temperaturehaving adsorbed materials from the wood drying process, a desorber at asecond temperature for receiving the sorbent and desorbing the adsorbedmaterials to form a gaseous stream comprising terpenes, and a coolingsystem, coupled to the desorber, wherein the cooling system isconfigured to condense a terpene stream from the gaseous stream, whereinthe terpene stream comprises alpha-pinene and/or beta-pinene.

In certain embodiments, the sorbent can comprise activated carbon.Additionally, the desorber can include one or more packed moving beds.In certain embodiments, the second temperature can be less than about572° F. Alternatively, the second temperature can range from about 302°F. to about 572° F. As embodied herein, the cooling system can include acondenser. In certain embodiments, the system can further include a firesuppression system. Additionally or alternatively, in certainembodiments, the desorber can include one or more access panels, e.g.,to provide access to the interior of the desorber during cleaning and/ormaintenance operations.

In certain embodiments, the sorbent can be maintained in the system atthe second temperature for less than about 2 hours. For example, thesorbent can be maintained at the second temperature for from about 30minutes to about 1.5 hours. The presently disclosed terpene streams insystems of the present disclosure can be sulfur-free. In certainembodiments, the gaseous stream of the present disclosure can furthercomprise nitrogen and/or steam. For example and not limitation, thegaseous stream can comprise at least 95 wt-% nitrogen. Additionally oralternatively, in addition to terpenes, the gaseous stream can include ahazardous air pollutant selected from the group consisting offormaldehyde, methanol, phenol, acrolein, acetaldehyde, propionaldehyde,fatty acids, acetic acid, and combinations thereof.

As embodied herein, systems for controlling the composition of terpenescollected from a wood drying process. Such systems can include a sorbentat a first temperature having adsorbed materials from the wood dryingprocess, a desorber at a second temperature for receiving the sorbentand desorbing the adsorbed materials to form a gaseous stream comprisingterpenes, and a cooling system, coupled to the desorber, wherein thecooling system is configured to condense a terpene stream from thegaseous stream, wherein the terpene stream comprises alpha-pinene and/orbeta-pinene. The desorber can include one or more packed moving beds.

Additional aspects of the present disclosure provide the followingembodiments.

Embodiment I: A method of controlling a composition of terpenescollected from a wood drying process, comprising: providing a sorbenthaving adsorbed materials from the wood drying process at a firsttemperature; heating the sorbent to a second temperature to release theadsorbed materials into a gaseous stream comprising terpenes; andcollecting a terpene stream from the gaseous stream, wherein the terpenestream comprises alpha-pinene and/or beta-pinene.

Embodiment II: The method of Embodiment I, wherein the secondtemperature is less than about 450° F.

Embodiment III: The method of any of Embodiments I or II, wherein theterpene stream comprises from about 0 wt-% to about 100 wt-%alpha-pinene and from about 0 wt-% to about 50 wt-% beta-pinene.

Embodiment IV: The method of any of Embodiments I through III, whereinthe terpene stream comprises from about 1 wt-% to about 20 wt-%alpha-pinene and from about 0 wt-% to about 20 wt-% beta-pinene.

Embodiment V: The method of any of Embodiments I through IV, furthercomprising maintaining the sorbent at the second temperature for lessthan about 2 hours.

Embodiment VI: The method of any of Embodiments I through V, wherein thesorbent is maintained at the second temperature for from about 30minutes to about 1.5 hours.

Embodiment VII: The method of any of Embodiments I through VI, whereinthe second temperature is less than about 430° F.

Embodiment VIII: The method of any of Embodiments I through VII, whereinthe second temperature is from about 390° F. to about 420° F.

Embodiment IX: The method of any of Embodiments I through VIII, whereinthe terpene stream comprises from about 50 wt-% to about 97 wt-% ofalpha-pinene and beta-pinene combined.

Embodiment X: The method of any of Embodiments I through IX, wherein theterpene stream comprises alpha-pinene in an amount of from about 20 wt-%to about 97 wt-%.

Embodiment XI: The method of any of Embodiments I through X, wherein theterpene stream comprises beta-pinene in an amount of from about 5 wt-%to about 60 wt-%.

Embodiment XII: The method of any of Embodiments I through XI, whereinthe terpene stream comprises from about 0 wt-% to about 20 wt-% ofdipentene.

Embodiment XIII: The method of any of Embodiments I through XII, whereinthe terpene stream comprises from about 0 wt-% to about 15 wt-% ofcamphene.

Embodiment XIV: The method of any of Embodiments I through XIII, whereinthe terpene stream is free of sulfur.

Embodiment XV: The method of any of Embodiments I through XIV, whereinthe gaseous stream further comprises nitrogen and/or steam.

Embodiment XVI: The method of any of Embodiments I through XV, whereinthe gaseous stream comprises at least 95 wt-% nitrogen.

Embodiment XVII: The method of any of Embodiments I through XVI, whereinthe gaseous stream further comprises a hazardous air pollutant selectedfrom the group consisting of formaldehyde, methanol, phenol, acrolein,acetaldehyde, propionaldehyde, fatty acids, acetic acid, andcombinations thereof.

Embodiment XVIII: The method of any of Embodiments I through XVII,wherein the sorbent comprises activated carbon.

Embodiment XIX: The method of any of Embodiments I through XVIII,wherein the sorbent is heated to the second temperature within adesorber comprising one or more packed moving beds.

Embodiment XX: The method of any of Embodiments I through XIX, whereinthe desorber includes one or more access panels.

Embodiment XXI: The method of any of Embodiments I through XX, whereincollecting the terpene stream from the gaseous stream comprisescondensing the terpene stream through a cooling system.

Embodiment XXII: The method of any of Embodiments I through XXI, whereinthe cooling system comprises a condenser.

Embodiment XXIII: A system for controlling a composition of terpenescollected from a wood drying process, comprising: a sorbent at a firsttemperature having adsorbed materials from the wood drying process; adesorber at a second temperature for receiving the sorbent and desorbingthe adsorbed materials to form a gaseous stream comprising terpenes; anda cooling system, coupled to the desorber, wherein the cooling system isconfigured to condense a terpene stream from the gaseous stream, whereinthe terpene stream comprises alpha-pinene and/or beta-pinene.

Embodiment XXIV: The system of Embodiment XXIII, wherein the sorbentcomprises activated carbon.

Embodiment XXV: The system of any of Embodiments XXIII or XXIV, whereinthe desorber comprises one or more packed moving beds.

Embodiment XXVI: The system of any of Embodiments XXIII through XXV,wherein the second temperature is less than about 572° F.

Embodiment XXVII: The system of any of Embodiments XXIII through XXVI,wherein the second temperature is from about 302° F. to about 572° F.

Embodiment XXVIII: The system of any of Embodiments XXIII through XXVII,wherein the cooling system comprises a condenser.

Embodiment XXIX: The system of any of Embodiments XXIII through XXVIII,further comprising a fire suppression system.

Embodiment XXX: The system of any of Embodiments XXIII through XXIX,wherein the desorber comprises one or more access panels.

Embodiment XXXI: The system of any of Embodiments XXIII through XXX,wherein the sorbent is maintained at the second temperature for lessthan about 2 hours.

Embodiment XXXII: The system of any of Embodiments XXIII through XXXI,wherein the sorbent is maintained at the second temperature for fromabout 30 minutes to about 1.5 hours.

Embodiment XXXIII: The system of any of Embodiments XXIII through XXXII,wherein the terpene stream is free of sulfur.

Embodiment XXXIV: The system of any of Embodiments XXIII through XXXIII,wherein the gaseous stream comprises at least 95 wt-% nitrogen.

Embodiment XXXV: The system of any of Embodiments XXIII through XXXIV,wherein the gaseous stream further comprises a hazardous air pollutantselected from the group consisting of formaldehyde, methanol, phenol,acrolein, acetaldehyde, propionaldehyde, fatty acids, acetic acid, andcombinations thereof.

Embodiment XXXVI: A method of controlling a composition of terpenescollected from a wood drying process, comprising: providing a sorbenthaving adsorbed materials from the wood drying process at a firsttemperature; heating the sorbent to a second temperature to release theadsorbed materials into a gaseous stream comprising terpenes; andcollecting a terpene stream from the gaseous stream, wherein the terpenestream comprises alpha-pinene and/or beta-pinene, wherein the sorbent isheated to the second temperature within a desorber comprising one ormore packed moving beds.

Embodiment XXXVII: A system for controlling a composition of terpenescollected from a wood drying process, comprising: a sorbent at a firsttemperature having adsorbed materials from the wood drying process; adesorber at a second temperature for receiving the sorbent and desorbingthe adsorbed materials to form a gaseous stream comprising terpenes; anda cooling system, coupled to the desorber, wherein the cooling system isconfigured to condense a terpene stream from the gaseous stream, whereinthe terpene stream comprises alpha-pinene and/or beta-pinene, whereinthe desorber comprises one or more packed moving beds.

The foregoing has outlined broadly the features and technical advantagesof the present application in order that the detailed description thatfollows can be better understood. Additional features and advantages ofthe application will be described hereinafter which form the subject ofthe claims of the application. It should be appreciated by those skilledin the art that the conception and specific embodiment disclosed can bereadily utilized as a basis for modifying or designing other structuresfor carrying out the same purposes of the present application. It shouldalso be realized by those skilled in the art that such equivalentconstructions do not depart from the spirit and scope of the applicationas set forth in the appended claims. The novel features which arebelieved to be characteristic of the application, both as to itsorganization and method of operation, together with further objects andadvantages will be better understood from the following description.

4. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 provides an illustration of a non-limiting example of an overallprocess flow schematic in accordance with certain embodiments of thepresently disclosed methods and systems.

FIG. 2 provides a schematic illustration of a non-limiting example of adesorber in accordance with certain embodiments of the presentlydisclosed methods and systems.

FIG. 3 provides a schematic illustration of a non-limiting example of acooling system, including a condenser, in accordance with certainembodiments of the presently disclosed methods and systems.

FIG. 4 provides a schematic illustration of a non-limiting example of anadsorber in accordance with certain embodiments and Example 1 of thepresent disclosure.

FIGS. 5A and 5B provide images of sorbent beads used in Example 1 of thepresent disclosure at 50× magnification. FIG. 5A shows an image of new(i.e., virgin) beads whereas FIG. 5B shows an image of spent beads.

FIG. 6 shows sorbent bead density and percentage organics as a functionof time in the adsorption trials of Example 1 of the present disclosure.

FIG. 7A shows sorbent bead density and hydrocarbon concentration at theoutlet of a fluidized bed over time, as measured during the pilot trialsof Example 2 of the present disclosure.

FIG. 7B shows the results of thermal gravimetric analysis on adsorbedsorbent, as described in Example 2 of the present disclosure. In the toppanel of FIG. 7B, the percentage organics as measured by thermalgravimetric analysis is overlaid with bead density. The bottom panelFIG. 7B shows the percentage of water adsorbed by the beads over time asmeasured by thermal gravimetric analysis.

FIG. 7C provides the terpenes yield, extrapolated over a year as afunction of run time, as calculated in Example 2 of the presentdisclosure.

FIG. 7D shows the results of thermal gravimetric analysis, carried outisothermally, on adsorbed sorbent as described in Example 2 of thepresent disclosure.

FIG. 7E compares the percentage reduction in volatile organic compounds(VOCs) (based on FID analysis) in a dryer exhaust stream afteradsorption and the percentage weight gain of the sorbent used foradsorption, as described in Example 2 of the present disclosure.

FIG. 7F shows the air flow at the inlet and outlet of the fluidized bedin terms of standard cubic feet per minute (scfm), dry standard cubicfeet per minute (dscfm), and actual cubic feet per minute (acfm) inaccordance with Example 2 of the present disclosure.

FIG. 7G compares the percentage reduction in VOCs (based on air samplesfrom impingers) in a dryer exhaust stream after adsorption and thepercentage weight gain of the sorbent used for adsorption, as describedin Example 2 of the present disclosure.

FIG. 7H compares the normalized terpene compositions in terpenesextracted from sorbent using thermal desorption as compared toliquid-liquid extraction at room temperature, as described in Example 2of the present disclosure.

FIG. 8A shows the percentage reduction in hazardous air pollutants(HAPs) methanol and formaldehyde over a 2.5 hour run time, as measuredby impingers in accordance with Example 3 of the present disclosure.

FIG. 8B compares the particulate matter concentration at the inlet ofthe fluidized bed and a conventional regenerative thermal oxidizer(RTO), as described in Example 3 of the present disclosure.

FIG. 8C compares the particulate matter reduction attributable to twodifferent pre-treatment set ups, as described in Example 3 of thepresent disclosure.

FIG. 8D shows the results of thermal gravimetric analysis oncommercially available gum turpentine within a pre-treatment system, asdescribed in Example 3 of the present disclosure.

FIG. 9 provides a schematic illustration of a non-limiting example of aglass desorption chamber used for the thermal desorption, as describedin Example 4 of the present disclosure.

FIG. 10 shows the temperature over time, along with the amount by weightof several commonly-found terpenes in a gaseous stream collected afterthermal desorption at a target temperature of about 200° F., asdescribed in Example 4 of the present disclosure.

FIG. 11A shows the sorbent apparent density as a function of time in theside stream reactivation trials of Example 6 of the present disclosure.

FIG. 11B shows the effect of side stream reactivation on sorbentapparent density, as described in Example 6 of the present disclosure.

FIG. 12A shows the sorbent apparent density as a function of time in theside stream reactivation trials of Example 6 of the present disclosure.

FIG. 12B shows the effect of side stream reactivation on sorbentapparent density, as described in Example 6 of the present disclosure.

FIG. 13 shows a relationship between condenser chiller temperature andTHC at the condenser outlet recycling back to desorber as described inExample 7 of the present disclosure.

FIG. 14A shows the relationship of adsorber differential pressure to theamount of THC inlet versus outlet, as described in Example 7 of thepresent disclosure.

FIG. 14B shows the percent of reduction efficiency and adsorberdifferential pressure across a second trial as described in Example 7 ofthe present disclosure where sorbent apparent density was maintained atabout 0.78 g/mL to about 0.805 g/mL.

FIG. 15 shows the percent of reduction efficiency and inlet versusoutlet THC across a trial as described in Example 8 of the presentdisclosure where sorbent apparent density was maintained at about 0.76g/mL to about 0.785 g/mL.

FIG. 16A shows percent reduction efficiency and inlet and outlet THC forbaseline and startup runs as described in Example 8 of the presentdisclosure.

FIG. 16B shows percent reduction efficiency and inlet and outlet THC fortwo runs, as described in Example 8 of the present disclosure.

FIG. 16C shows percent reduction efficiency and inlet and outlet THC fortwo runs, as described in Example 8 of the present disclosure.

FIG. 17 shows the effect of sorbent temperature and time on percentreduction efficiency, carbon temperature, and apparent density, asdescribed in Example 9 of the present disclosure.

FIG. 18A shows the terpene yield with time based on a run, as describedin Example 9 of the present disclosure.

FIG. 18B shows the extrapolated terpene yield with time based on a fullcommercial system, as described in Example 9 of the present disclosure.

FIG. 19 shows the terpene yield based on a full commercial system, asdescribed in Example 9 of the present disclosure. The axis displayingrun time has tick marks corresponding to every two days over a forty dayperiod.

FIG. 20A shows the breakdown between alpha-pinene or beta-pinene versusother terpene products and fatty acids, in accordance with Example 9,where the desorber operating at about 425° F. FIG. 20B shows thebreakdown between alpha-pinene or beta-pinene versus other terpeneproducts and fatty acids, in accordance with Example 9, where thedesorber is operating at between about 450-600° F. FIG. 20C shows thebreakdown between alpha-pinene or beta-pinene versus other terpeneproducts and fatty acids, in accordance with Example 9, where thedesorber is operating at between about 500° F. FIGS. 20A, 20B, and 20Cprovide of series of terpene analysis. In the figures, the specificpercentage of each terpene is identified from bottom to top in thefollowing order: alpha-pinene, camphene, beta-pinene, o-cymene,(D)-limonene, p-cymene, fatty acids (C18), and total (other).

FIG. 21 shows a second series of terpene analysis conducted for variousruns, as described in Example 9 of the present disclosure. FIG. 21provides a series of terpene analysis. In the figures, the specificpercentage of each terpene is identified from bottom to top in thefollowing order: alpha-pinene, camphene, beta-pinene, o-cymene,(D)-limonene, p-cymene, and total (other).

FIG. 22 shows a third series of terpene analysis conducted for variousruns, as described in Example 9 of the present disclosure. FIG. 22provides a series of terpene analysis. In the figures, the specificpercentage of each terpene is identified from bottom to top in thefollowing order: alpha-pinene, camphene, beta-pinene, o-cymene,(D)-limonene, p-cymene, and total (other).

FIG. 23 shows a plot of the operational measurement trends of carbontemperature, apparent density, and percent reduction efficiency, asdescribed in Example 9 of the present disclosure.

5. DETAILED DESCRIPTION

The presently disclosed subject matter provides methods and systems forcontrolling emissions, specifically, from exhaust streams created bywood drying operations. These and other aspects of the disclosed subjectmatter are discussed more in the detailed description and examples.

5.1 Definitions

The terms used in this specification generally have their ordinarymeanings in the art, within the context of this subject matter and inthe specific context where each term is used. Certain terms are definedbelow to provide additional guidance in describing the compositions andmethods of the disclosed subject matter and how to make and use them.

As used in the specification and the appended claims, the singular forms“a”, “an”, and “the” include plural referents unless the context clearlydictates otherwise. Thus, for example, reference to “a compound”includes mixtures of compounds.

The term “about” or “approximately” means within an acceptable errorrange for the particular value as determined by one of ordinary skill inthe art, which will depend in part on how the value is measured ordetermined, i.e., the limitations of the measurement system. Forexample, “about” can mean within 3 or more than 3 standard deviations,per the practice in the art. Alternatively, “about” can mean a range ofup to 20%, preferably up to 10%, more preferably up to 5%, and morepreferably still up to 1% of a given value. Alternatively, particularlywith respect to systems or processes, the term can mean within an orderof magnitude, preferably within five-fold, and more preferably withintwo-fold, of a value.

“Coupled” as used herein refers to the connection of a system componentto another system component by any means known in the art. The type ofcoupling used to connect two or more system components can depend on thescale and operability of the system. For example, and not by way oflimitation, coupling of two or more components of a system can includeone or more joints, valves, transfer lines, or sealing elements.Non-limiting examples of joints include, but are not limited to,threaded joints, soldered joints, welded joints, compression joints, andmechanical joints. Non-limiting examples of fittings include, but arenot limited to, coupling fittings, reducing coupling fittings, unionfittings, tee fittings, cross fittings, and flange fittings.Non-limiting examples of valves include, but are not limited to, gatevalves, globe valves, ball valves, butterfly valves, and check valves.

As used herein, “terpenes” refers to volatile organic compounds fromplants, which are derived from isoprene. For example, monoterpenesinclude two isoprene units and have the general formula C₁₀H₁₆.

“Dipentene,” as used herein, refers to a class of compounds including 10carbon atoms and having multiple double bonds and a closed 6-memberring, such as limonene (e.g., d-limonene and/or 1-limonene),terpinolene, alpha-terpinene, and gamma-terpinene.

5.2 Systems for Recovering Terpene Composition

In certain aspects, the present disclosure provides systems forrecovering terpenes collected from a wood drying process, and forcontrolling the composition of such terpenes. The systems can include asorbent that has adsorbed materials from the wood drying process and adesorber that receives the sorbent and desorbs the adsorbed materialsfrom the sorbent to form a gaseous stream comprising terpenes. Thesystem can further include a cooling system, coupled to the desorber, tocondense the terpenes from the gaseous stream. The terpenes collected inaccordance with the present disclosure have a desirable amount ofalpha-pinene and beta-pinene relative to other terpenes, such asdipentene and camphene. In certain embodiments, systems of the presentdisclosure do not require a Regenerative Thermal Oxidizer (RTO).Further, in particular embodiments, methods of the present disclosure donot require thermal oxidation.

5.2.1 Overview

FIG. 1 provides an illustrative overview of a non-limiting example of aprocess flow schematic in accordance with embodiments of the presentdisclosure. In FIG. 1 , an exhaust stream, such as that from a wooddryer, is optionally heated in a heat exchanger 914 located upstream ofan adsorber fan 913. Upon heating, the exhaust stream then optionallypasses through a pre-treatment unit 901 as described in the presentlydisclosed subject matter, where certain particulate matter and/or VOCs,can be filtered or removed from the exhaust stream. Alternatively, incertain embodiments, an exhaust stream, such as that from a wood dryer,can pass through an adsorber fan located upstream of a pre-treatmentunit optionally including a heat exchanger for heating the exhauststream.

Fresh sorbent, such as but not limited to fresh carbon, is supplied to aload hopper 909. The load hopper 909 houses sorbent until the sorbent isneeded and fed to an adsorber 902.

After the exhaust stream is pre-treated in the pre-treatment unit 901,it can be routed into an adsorber 902 at an inlet location toward thebottom of the adsorber 902. A separate sorbent stream from a load hopper909 and/or a desorber separation pot 907 is fed to the adsorber 902 atan inlet location toward the top of the adsorber 902. In the adsorber902, the upflowing exhaust stream is contacted with the downflowingsorbent stream, and certain compounds, emissions particulates, VOCs,and/or HAPs are adsorbed onto the sorbent. A clean exhaust stream, whichis exits at the top of the adsorber 902 can be vented to a downstreamlocation and/or to the atmosphere.

Spent sorbent exits the adsorber 902 and is directed to, for example andnot limitation, an adsorber eductor 904 or airlift blower, to whichfresh air can be supplied by an air blower 915. The spent sorbent streamis directed to an adsorber separation pot 906 or adsorber separatorbefore spent sorbent enters a desorber 903. Spent sorbent containingadsorbed emissions particulates and compounds from an upstream wooddrying process is desorbed in the desorber 903, which releases adsorbedmaterials from the spent sorbent. A nitrogen blower 910, supplied from anitrogen source, recirculates nitrogen and air flow through the desorber903 to facilitate desorption of the sorbent. The VOCs can be furtherpassed through a secondary adsorber in desorber.

Reactivated sorbent that has been desorbed in the desorber 903 can berouted via a desorber eductor 905 to a desorber separation pot 907 ordesorber separator. Reactivated sorbent, which has had adsorbedmaterials removed by the desorber 903, can be circulated and fed backinto the adsorber 902 to adsorb exhaust stream.

A slip stream or side stream from the desorber separation pot 907 can berouted to a side stream reactivator 908. The side stream reactivator 908provides further sorbent reactivation, releasing any additional adsorbedmaterials from the sorbent that was not desorbed and removed in thedesorber 903. Reactivated sorbent from the side stream reactivator 908is then routed to load hopper 909 or adsorber 902, and can be suppliedto the adsorber 902 as sorbent is needed.

The desorber 903 can also be coupled to a condenser 912. A mixturestream of desorbed materials and nitrogen is routed from the desorber903 to the condenser 912. A chiller or other cooling source can provideheat exchange in the condenser 912. Nitrogen separated from desorbedmaterials, including terpenes, is recycled and circulated from thecondenser 912 back to the desorber 903. Desorbed materials, such asterpenes, is routed from the condenser 912 to a decanter 911 usedprimarily to separate the water from the terpenes. Recovered terpeneproducts can then be stored for further commercial purposes.Alternatively, a mixed stream of desorbed materials and nitrogen can berouted to an incinerator to incinerate VOCs. Such process, althougheconomically viable, can be less desirable for not providing recovery ofterpenes and increasing greenhouse gas emissions.

5.2.2 Sources of Exhaust Streams

The systems and methods of the present disclosure can be used to recoverterpenes from exhaust streams from various wood drying operations. Wooddrying is used during the processing and manufacturing of manywood-based products to control moisture content, and can sometimes occurat multiple stages within various manufacturing processes. Drying woodcan make it more suitable for construction or woodworking purposes, orreduce moisture content to increase the combustibility of the wood.

For example, and not limitation, wood dryers can be used during themanufacturing of construction materials, including, but not limited to,oriented strand board (OSB or flakeboard), plywood, fiberboard(including medium-density fiberboard or MDF), particle board, lumber,scrimber, hardboard, parallel strand lumber, laminated wood products(such as laminated timber, laminated veneer, laminated strand board,laminated strand lumber, and cross-laminated timber), wood composites(including transparent wood composites), and various beams, joints,trusses, and other wood products. Additionally, wood dryers can be usedin the manufacturing of wood-based biofuels, such as wood pellets. Thus,as embodied herein, the exhaust stream can be obtained from one or moreof these manufacturing processes, or any other manufacturing processinvolving the drying of wood. In particular embodiments, the wood dryingprocess occurs during the manufacture of oriented strand board and/orplywood, and wood pellets.

In large-scale manufacturing processes, wood dryers can be ovens orkilns that can heat wood over a certain period of time. In certainembodiments, rotary dryers can be used, including single- or multi-passrotary dryers. Alternatively, one or more flash tube dryers can be used.Some operations recycle a portion of the dryer exhaust gas back into theentrance of the dryer as a dryer energy reduction, emissions control,and wood drying control measure. The dryers can be heated indirectly,e.g., using steam, or directly fired, e.g., with wood, natural gas,and/or fuel oil burners. The wood being dried can be in any suitableform during heating, including, by way of example and not limitation, aslogs, veneers, boards, pellets, chips, flakes, pulp, etc. The dryingprocess is typically controlled based on the supply (mass flow) of woodto the wood dryers, which can ensure even heating, and temperaturecontrols, to minimize moisture and prevent overheating. The dryingprocess can be controlled based on the outlet temperature of the dryer(which can be a function of moisture release, e.g., in rotary dryers).The outlet temperature can be based, for example and not limitation, onwet bulb temperature, dry bulb temperature, relative temperature, or themoisture of the wood outputted from the dryer. In certain embodiments,the temperature can be measured and controlled at two or more pointsalong the length of the drying cycle to create a drying profile. Assuch, temperature and/or moisture sensors can be placed within the dryerand/or at the dryer outlet and/or inlet. A person of skill in the artwill appreciate that the type of control can be based on the type ofdryer or kiln used in the wood drying process. In certain processes, thewood can be air dried or humidified (e.g., sprayed with water) prior todrying to ensure that all wood supplied to the wood dryer has similarmoisture content.

As wood is heated during the drying process, it is known to releaseseveral VOCs and their thermal decomposition products into the dryerexhaust streams. For example and not limitation, such VOCs and thermaldecomposition products can be found in the lignin, cellulose,hemicellulose, and resin of trees. Many of these VOCs are terpenes orturpentine, although the exhaust can also include other HAPs.Commonly-found HAPs include formaldehyde, methanol, phenol, acrolein,acetaldehyde, and/or propionaldehyde, although other HAPs can also befound in the process exhaust stream. Exhaust from wood drying processescan additionally include air and steam, and can further includeundesirable emissions other than VOCs and HAPs, such as particulatematter, carbon monoxide, carbon dioxide, NOR emissions, and/or inorganicemissions, such as inorganic compounds containing potassium, silicon,sulfur, chlorine, calcium, manganese, magnesium, antimony, arsenic,beryllium, cadmium, chromium, cobalt, mercury, nickel, phosphorus,sodium, lead, rubidium, iron, copper, and/or zinc.

In the present disclosure, “process exhaust stream” is used to refer toexhaust released directly from a wood dryer, e.g., containing air,steam, VOCs, HAPs (such as formaldehyde, methanol, phenol, acrolein,acetaldehyde, and/or propionaldehyde), particulate matter, carbonmonoxide, carbon dioxide, NOR, and/or inorganic compounds. As embodiedherein, and for example and not limitation, the volume of the processexhaust stream supplied to a downstream adsorber can range from about 50cfm to about 500,000 cfm, or from about 100 cfm to about 500,000 cfm, orfrom about 500 cfm to about 500,000 cfm, or from about 1,000 cfm toabout 500,000 cfm, or from about 10,000 cfm to about 500,000 cfm, orfrom about 20,000 cfm to about 100,000 cfm, or from about 50,000 cfm toabout 100,000 cfm, or from about 100,000 cfm to about 500,000 cfm, orfrom about 100,000 cfm to about 300,000 cfm. In certain embodiments, thevolume of the process exhaust stream supplied to a downstream adsorbercan range from about 75 cfm to about 200,000 cfm, or from about 100 cfmto about 100,000 cfm, or from about 125 cfm to about 90,000 cfm, or fromabout 150 cfm to about 80,000 cfm, or from about 175 cfm to about 70,000cfm, or from about 200 cfm to about 60,000 cfm, or from about 225 cfm toabout 50,000 cfm, or from about 250 cfm to about 40,000 cfm, or fromabout 275 cfm to about 30,000 cfm, or from about 300 cfm to about 20,000cfm, or from about 300 cfm to about 10,000 cfm. In certain embodiments,the volume of the process exhaust stream supplied to a downstreamadsorber can be from about 250 cfm to about 325 cfm. In particularembodiments, the volume of the process exhaust supplied to a downstreamadsorber can be about 300 cfm.

The content and composition of the process exhaust stream can depend onthe type of wood used, as wood drying processes are applied to a largenumber of different woods. Such woods include, but are not limited to,softwoods, such as cedars, firs, spruces, pines, larch, hemlock,juniper, redwood, and yew, and/or hardwoods, such as birches, elms,maples, eucalyptus, alder, ash, aspen, oak, poplar, bamboo, basswood,beech, cottonwood, and willow. Additionally, various other factors canaffect the content and composition of the exhaust stream, including, butnot limited to, the age of the wood and its geographic source.Environmental, harvesting (from cutting to drying), and weatherconditions before and after harvesting the wood can also impact thecomposition of the exhaust stream when the wood is dried.

5.2.3 Desorbers

As embodied herein, a system for controlling terpene compositionincludes a desorber which can receive a spent sorbent from an upstreamadsorber containing adsorbed emissions from a wood drying process. Thedesorber can release adsorbed materials from the sorbent, e.g., usingthermal desorption, supercritical CO₂ desorption, solvent extraction,and/or steam stripping.

Materials adsorbed on the sorbent can include VOCs (e.g., terpenes),HAPs, and/or particulate matter from a wood drying process. The sorbentcan be any sorbent that is suitable for removing these emissions from anexhaust stream from the wood drying process. For example, and withoutlimitation, the sorbent can include beads, particles, or a combinationthereof. The sorbent can be made of any suitable material, including,but not limited to, carbon (including activated carbon), zeolite, silica(e.g., fumed silica or silica gel), purolytic synthetic material,polymeric material, activated alumina, bauxite, clays (e.g., amorphous,crystalline, and/or mixed layer clays), iron oxide, magnesium oxide,magnesium silicate, molecular sieves, zirconium oxide, and combinationsthereof. In certain embodiments, the beads or particles can benanoporous, including microporous (e.g., having a pore size less than 2nm), mesoporous (e.g., having a pore size from 2 nm to 50 nm), and/ormacroporous (e.g., having a pore size greater than 50 nm) beads andparticles. In certain embodiments, the sorbent can comprise activatedcarbon, including bead activated carbon (BAC). Activated carbon can alsobe in the form of carbon fiber, chop, felt, or yarn, or can be powdered,granularized, pelletized, or embedded in a cloth. As embodied herein,the activated carbon can optionally be impregnated to improve adsorptionefficiency, e.g., of one or more specific VOCs.

Examples of activated carbon suitable for use with the presentdisclosure include, but are not limited to, Bead-Shaped Activated Carbon(from Kureha America, LLC) or other forms of spherical activated carbon(such as those available from Blucher GmbH). In certain embodiments, thesorbent can comprise polymer materials, such as those described in U.S.Pat. Nos. 8,999,202; 9,133,295; 9,133,337; 9,464,162; 9,598,525;9,714,172; U.S. Patent Pub. No. US20130209348A1; and U.S. Patent Pub.No. US20150329364A1, the contents of which are hereby incorporated byreference in their entireties. In certain embodiments, the sorbent cancomprise Dowex resin beads (from Dow Chemical Company).

Sorbents for use in the present disclosure can have any suitable sizeand shape. For example, the sorbent can be spherical, granular,pelletized, or a combination thereof. As used herein, the term “beads”refers to a generally spherical sorbent. The size of the sorbent can befrom about 10 microns to about 10 mm, or from about 10 microns to about4 mm, or from about 10 microns to about 800 microns, or from about 400microns to about 700 microns.

Generally, the amount of the sorbent can be selected based on theexpected amount of material to be adsorbed. For example, the capacity ofthe sorbent can be up to about 75%, or up to about 50% of the initialweight of the sorbent. In certain embodiments, it is preferred that theamount of material adsorbed during operation is from about 10% to about50%, or from about 15% to about 33%, or at least about 20% of theinitial weight of the sorbent. In particular embodiments, the amount ofmaterial adsorbed during operation can be about 35% of the initialweight of the sorbent. Generally, the amount of the sorbent can beselected based on the expected amount of material to be adsorbed. Forexample, in certain embodiments, the weight of sorbent can be from about2 times to about 10 times, or from about 5 times to about 7 times, theweight of material expected to be adsorbed.

Sorbent particles can also be defined by their density, bulk density,void fraction, size distribution, and terminal velocity. For example,and not limitation, the apparent density of the virgin sorbent can befrom about 0.1 g/mL to about 5 g/mL, or about 0.2 g/mL to about 2 g/mL,or about 0.3 g/mL to about 1 g/mL, or about 0.6 g/mL. The apparentdensity of spent sorbent or reactivated can be greater than that ofvirgin sorbent, e.g., from about 0.5 g/mL to about 1.5 g/mL, or fromabout 0.6 g/mL to about 0.9 g/mL. During operation, the apparent densityof the sorbent can be from about 0.1 g/mL to about 1.5 g/mL, or fromabout 0.5 g/mL to about 1 g/mL, or from 0.78 g/mL to about 0.81 g/mL, orfrom about 0.81 g/mL to about 0.813 g/mL, or from about 0.55 g/mL toabout 0.9 g/mL, or from about 0.6 g/mL to about 0.8 g/mL, or from about0.6 g/mL to about 0.7 g/mL. In certain embodiments, the apparent densityof the sorbent can be about 0.6 g/mL, or about 0.62 g/mL, or about 0.64g/mL, or about 0.66 g/mL, or about 0.68 g/mL, or about 0.7 g/mL, orabout 0.72 g/mL, or about 0.74 g/mL, or about 0.76 g/mL, or about 0.78g/mL, or about 0.785 g/mL, or about 0.8 g/mL, or about 0.803 g/mL, orabout 0.805 g/mL, or about 0.81 g/mL, or about 0.81 g/mL. In certainembodiments, the apparent density of the sorbent is maintained at orbelow 0.79 g/mL, or at or below 0.785 g/mL, or at or below 0.78 g/mL, orat or below 0.775 g/mL, or at or below 0.77 g/mL, or at or below 0.765g/mL, or at or below 0.76 g/mL, or at or below 0.755 g/mL, or at orbelow 0.75 g/mL. As embodied herein, the apparent density can bemeasured by the ASTM Standard Test Method for Apparent Density ofActivated Carbon (Designation D 2854-96), the contents of which arehereby incorporated by reference in their entirety. In certainembodiments, the bead density of the sorbent can be from about 0.4 g/mLto about 0.7 g/mL or from about 0.5 g/mL to about 0.7 g/mL. Inparticular embodiments, the bead density of the sorbent can be about0.584 g/mL, about 0.603 g/mL, about 0.6 g/mL, about 0.611 g/mL, about0.618 g/mL, about 0.630 g/mL, or about 0.633 g/mL.

In certain embodiments, the Brunauer-Emmett-Teller (BET) surface area ofthe virgin sorbent can be from about 500 m²/g to about 2000 m²/g, orfrom about 700 m²/g to about 1500 m²/g, or from about 1000 m²/g to about1200 m²/g, whereas the BET surface area of the spent sorbent can be lessthan about 20 m²/g, or less than about 15 m²/g, or less than about 10m²/g.

The desorber can include one or more beds to which spent sorbent can beprovided, and in which the desorption can occur. For example, and notlimitation, packed moving beds and fluidized beds are suitable for usein the presently disclosed desorbers. Alternatively, in certainembodiments, a rotary calciner can be used in the desorber, such thatthe rotation of the rotary calciner creates a falling bed. As embodiedherein, and in certain embodiments, sorbent from the adsorber can bedirected to two or more beds within the desorber using a distributor. Incertain embodiments, the beds can be generally tubular. In certainembodiments, the desorber includes packed moving beds. The capacity ofthe desorber can be controlled by adjusting the number and the diameterand length of the beds.

As embodied herein, an inert gas stream can be provided to the desorbervia a gas line. In particular embodiments, the inert gas stream can beprovided to the desorber via a blower. The inert gas can reduce thepresence of oxygen in the desorber, reducing the chance of auto-ignitionof released volatile compounds. In certain embodiments, the inert gasstream can be maintained at an operational makeup pressure between about30 inches of water to about 50 inches of water, between about 35 inchesof water to about 45 inches of water, or between about 37 inches ofwater to about 43 inches of water. In certain embodiments, theoperational recirculation rate of the inert gas stream can be maintainedbetween about 7 cfm to about 11 cfm, between about 8 cfm to about 10cfm, or between about 8.5 cfm to about 9.1 cfm. In particularembodiments, the operational recirculation rate of the inert gas streamcan be maintained at about 7 cfm, about 8 cfm, about 9 cfm, about 10cfm, or about 11 cfm. The inert gas stream can be supplied into thesystem by a blower having an operational blower outlet pressuremaintained between about 26 inches of water to about 34 inches of water,from about 28 inches of water to about 34 inches of water, or from about29 inches of water to about 32 inches of water.

Suitable inert gases include, but are not limited to, nitrogen (N₂),liquid supercritical CO₂, and superheated steam. In particularembodiments, the inert gas comprises nitrogen (N₂). After release ofvolatile compounds, the gaseous stream within the desorber can remainpredominantly inert gas, e.g., at least 95 wt-% or at least 98 wt-%nitrogen (N₂). The inert gas can thus act as a carrier gas to transportdesorbed terpenes to a cooling system, e.g., via one or more transportlines. When cooled, the recovered terpenes can be condensed from theinert gas, and the inert gas can be recycled, further routed fordownstream processing, and/or released into the atmosphere. Thus, thepresently disclosed system can further include one or more recyclelines, alternative processing lines, and/or vents for transporting inertgas from the cooling system.

Additionally, in embodiments based on thermal desorption, the bed(s) canbe provided with seal sections, and the capacity of the desorber can befurther controlled by adjusting the relative amount of the bed(s) opento desorption versus closed by the seal sections. Generally, theconfiguration of one or more beds within the desorber can be designed toimprove flow of sorbent and prevent plugging of the desorber. For thepurpose of illustration and not limitation, FIG. 2 provides a schematicof a desorber in accordance with the presently disclosed subject matter.As shown in FIG. 2 , spent sorbent 201 containing adsorbed material canbe provided towards the top of the desorber. An exit for overflow 202can be provided to remove any excess sorbent that accumulates at the topof the desorber, and also ensure the desorber remains full of sorbent.

Sorbent can flow downwards through the desorber to a first set of sealtubes 211. The seal tubes 211 can form a seal to prevent air fromentering and increasing the oxygen content of gas in a preheat section215 below the first set of seal tubes 211. In the preheat section 215,the sorbent is pre-heated (e.g., up to about the flash point of theadsorbed terpenes, or above the flash point of adsorbed terpenes but inthe presence of inert gas) but the adsorbed material is not yetdesorbed. Preheating the sorbent can facilitate removal of water fromsorbent in upper section of the desorber. In some embodiments, water canbe released in the preheating section. In certain embodiments, sorbentcan be preheated to a temperature in a range of from about 100° F. toabout 400° F., from about 200° F. to about 400° F., or from about 210°F. to about 400° F. For example and not by limitation, sorbent can bepreheated to a temperature of about 125° F., or about 150° F., or about175° F., or about 200° F., or about 225° F., or about 250° F., or about275° F., or about 300° F.

The sorbent then flows downwards to a main heating section 225 fordesorption. The main heating section 225 is isolated from the preheatsection 215 with a second set of seal tubes 212. Following desorption,the sorbent can be fed to a cooling section 235 and removed from thedesorber, e.g., and recycled back to an adsorber or sorbent reactivationsystem. The sorbent can be removed via a bottom section 245, which canhave an overall conical shape to facilitate the movement of sorbent. Incertain embodiments, the bottom section 245 of the desorber has acooling capability to cool the sorbent prior to reintroduction into anadsorber coupled with the desorber. Such a cooling capability canfurther enhance adsorption and emission control because cooling thesorbent makes it less likely to desorb VOCs when reintroduced into theadsorber.

Within the desorber, the sorbent can encounter countercurrent flow withan inert gas, such that the inert gas strips the sorbent of the adsorbedmaterial. For example, as shown in FIG. 2 , the inert gas 205 can enterat a carrier gas inlet section 228 located below the main heatingsection 225. The inert gas can flow upwards, counter to the sorbent, andexit as a recycle stream 209 above the main heating section 225,preferably above the pre-heating section 215, such that it provides aninert environment as the sorbent is heated.

The desorbed gaseous stream 203 can exit the desorber immediately abovethe main heating section 225 such that desorbed terpenes are not fed tothe preheat section 215. The desorbed gaseous stream can be sent to adownstream condenser for terpene recovery and after being stripped ofterpenes and other VOCs, the gaseous stream can be recycled back to thedesorber. For example, the recycled gaseous stream 207 can be recycledto a secondary adsorber section 213 for further recovery of terpenesand/or purification of the gaseous stream. In alternative embodiments,the desorbed gaseous stream 203 can be incinerated.

The desorber can further include various components to control theprocess conditions during desorption. In certain embodiments, thedesorber can include a heater or heat exchanger to control thetemperature within the desorber. For example, in particular embodiments,an electrical immersion heater can be used within the desorber, whichcan minimize temperature variation within the desorber. In alternativeembodiments, oil, natural gas, or superheated steam can be used to heatthe desorber.

For example, in certain embodiments a hot oil can be circulated toindirectly heat the contents of the desorber. For example, and as knownin the art, the wood drying and manufacturing processes disclosed hereincan include the use of hot oil, e.g., in presses used in the manufactureof various wood products including oriented strand board. Such hot oilcan be circulated to the desorber for heating.

In alternative embodiments, at least one heat exchanger having a tubeand shell configuration can be used within the desorber. In particularembodiments, such configuration can increase uniform temperature controland consistency within the desorber. Such desorbers include thermal oilheated desorbers. For example, in certain embodiments, in the desorber,sorbent can form on a moving bed flowing downward through a tube andshell heat exchanger to heat the sorbent. After heating, the moving bedcan pass over a carrier gas diffuser and enter a cooler as desorbed orclean activated sorbent. The cooler can be a tube and shell heatexchanger designed to remove the previously added heat from the sorbent.After the heat is removed, the sorbent is desorbed and transferred backto the adsorber.

In certain embodiments, a preheater can be used to heat sorbent in orderto release water from the sorbent in an upper section of the desorber.Such system can be operated between about 212° F. and a boiling point ofan organic solvent to be collected. For example and not by way oflimitation, the preheater can be maintained at a temperature of fromabout 212° F. to about 300° F., from about 212° F. to about 250° F., orat about 225° F.

In certain embodiments, the operating temperature of the desorber can bemaintained at about 600° F., or at about 575° F., or at about 550° F.,or at about 525° F., or at about 500° F., or at about 475° F., or atabout 450° F., or at about 437° F., or at about 430° F., or at about425° F., or at about 410° F., or at about 400° F., or at about 375° F.,or at about 350° F., or at about 325° F., or at about 300° F. Inembodiments of the present disclosure, the operating temperature of thedesorber can be maintained between about 320° F. to about 530° F., about360° F. to about 450° F., or between about 365° F. to about 445° F., orbetween about 370° F. to about 440° F., or between about 375° F. toabout 435° F., or between about 380° F. to about 430° F., or betweenabout 385° F. to about 425° F., or between about 390° F. to about 420°F., or between about 390° F. to about 430° F., or between about 395° F.to about 415° F. In certain embodiments, the operating temperature ofthe desorber can be maintained at about 400° F., about 410° F., or about430° F.

The operating pressure of the desorber can be adjusted and maintained bya person of ordinary skill in the art. In certain embodiments, theoperating pressure of the desorber can be maintained between about 1inch of water to about 110 inches of water, about 1 inch of water toabout 100 inches of water, about 15 inches of water to about 100 inchesof water, about 50 inches of water to about 100 inches of water, about75 inches of water to about 100 inches of water, about 15 inches ofwater to about 50 inches of water, about 25 inch of water to about 50inches of water, about 25 inches of water to about 35 inches of water,about 28 inches of water to about 32 inches of water, or between about 1inch of water to about 40 inches of water, or between about 2 inches ofwater to about 40 inches of water, or between about 2 inches of water toabout 35 inches of water, or between about 3 inches of water to about 22inches of water, or between about 3 inches of water to about 20 inchesof water, or between about 4 inches of water to about 18 inches ofwater, or between about 4 inches of water to about 15 inches of water,or between about 5 inches of water to about 12 inches of water, orbetween about 5 inches of water to about 10 inches of water, or betweenabout 5 inches of water to about 8 inches of water. In particularembodiments, the operating pressure of the desorber can be maintained atabout 20 inches of water, about 25 inches of water, about 28 inches ofwater, about 29 inches of water, about 30 inches of water, about 31inches of water, about 32 inches of water, or about 35 inches of water.

The desorber can optionally include one or more additional components.For example, the desorber can include a fire suppression system toreduce the likelihood of deflagration within the desorber. For example,CO₂ or N₂ suppression can be used. Other fire suppression systems arealso suitable for use with the presently disclosed desorber, includingPeltier (thermoelectric) cooling systems (preferably made of metal) andHalon suppression systems. Additionally or alternatively, the desorbercan include various valves, which can act as safety features to preventdeflagration within the desorber.

In certain embodiments, fire containment features can be included in thesystem, e.g., within or around the desorber. For example, the desorbercan include fire resistant foam insulation, or can be disposed in afireproof environment, such as a cement enclosure or underground.

5.2.4 Systems for Conveying Sorbent

As embodied herein, the system can further include components forproviding the sorbent to and from the desorber. The components describedherein can be used to automatically or manually load and unload sorbentfrom the desorber.

In certain embodiments, sorbent can be desorbed in a batch, semi-batch,or continuous process. In particular embodiments, the sorbent can berecirculated in a continuous process. Once desorbed, the sorbent can bereturned directly or indirectly (e.g., after passing through a sidestream reactivation process) to an adsorption system. Additionally oralternatively, sorbent can be periodically removed from the system forcleaning and reactivation prior to being reintroduced to the adsorptionsystem.

The sorbent can be conveyed within the system using any suitable means,as known in the art. For example, and not limitation, sorbent can beconveyed using airlift eductors, fans, pneumatics, nozzles, etc.Advantageously, orifices can be included within airlift systems tominimize airflow variation and to minimize variation in sorbent transferrate. In certain embodiments, airlift systems can be advantageouslyheated with heat trace and/or insulated to prevent water condensationwithin the airlift systems, which can prevent sorbent flow in theoverall adsorption system. A sorbent sampling system can be provided inorder to periodically examine, test, and sample the sorbent (e.g., forapparent density) and improve accuracy of the adsorption system.

One of ordinary skill in the art can adjust operating conditions suchthat sorbent can be transferred from and through the desorber. Incertain embodiments, sorbent can be transferred through the desorber ata rate of from about 10 pounds per hour to about 100 pounds per hour, orfrom about pounds per hour to about 95 pounds per hour, or from about 20pounds per hour to about 90 pounds per hour, or from about 25 pounds perhour to about 85 pounds per hour, or from about 30 pounds per hour toabout 80 pounds per hour, or from about 30 pounds per hour to about 50pounds per hour, or from about 35 pounds per hour to about 75 pounds perhour, or from about 35 pounds per hour to about 80 pounds per hour, orfrom about 40 pounds per hour to about 80 pounds per hour, or from about45 pounds per hour to about 80 pounds per hour, or from about 50 poundsper hour to about 90 pounds per hour, or from about 50 pounds per hourto about 80 pounds per hour, or from about 55 pounds per hour to about80 pounds per hour, or from about 60 pounds per hour to about 80 poundsper hour. A person of ordinary skill in the art will appreciate theoperating conditions can be adjusted such that sorbent can betransferred through the desorber at a rate as needed (e.g., at 1000pounds per hour or greater for larger systems).

5.2.5 Cooling Systems

In certain embodiments, the desorbed gaseous stream from the desorbercan be condensed into a liquid stream using a cooling system, such as acondenser. In the condenser, the hot gaseous stream can contact acondenser coil containing a chilled condenser fluid. For example and notlimitation, FIG. 3 provides a schematic illustration of a cooling systemincluding a condenser. As shown in FIG. 3 , liquid condensate containingterpenes can be recovered at the bottom of the condenser. In particularembodiments, the condenser fluid can include water, e.g., water mixedwith glycol, cooling tower water, or chilled water. Alternatively, thecondenser can be air cooled. As embodied herein, the condenser can becooled to an operating temperature of about 0° F. to about 125° F.,preferably less than about 100° F. In certain embodiments, the condensercan be cooled to an operating temperature of about 120° F., or about115° F., or about 110° F., or about 105° F., or about 100° F., or about95° F., or about 90° F., or about 85° F., or about 80° F., or about 75°F., or about 70° F., or about 65° F., or about 60° F., or about 55° F.,or about 50° F., or about 45° F., or about 40° F., or about 35° F., orabout 30° F. The condenser can be coupled with a chiller (e.g., a gylcolchiller), which provides cooling to the condenser. As embodied herein,the condenser coupled with a chiller (i.e., a condenser chiller) canhave an operating temperature of about 0° F. to about 50° F., about 40°F. to about 50° F., or about 32° F. to about 39° F. In certainembodiments, the condenser chiller can have an operating temperature ofabout 0° F., about 34° F., about 35° F., or about 45° F. The condenserchiller can have a pressure of about 41 psi to about 45 psi. In certainembodiments, the condenser chiller can have a pressure of about 43 psi.Additionally or alternatively, cooling of the gaseous stream can beeffected using expansion (Venturi) cooling.

The gaseous stream can be passed through the cooling system for one,two, or more passes. In certain embodiments, the condenser is configuredfor one pass. In other certain embodiments, the gaseous stream passesthrough the cooling system at least twice. Additionally, once terpeneshave been condensed from the gaseous stream, the stripped gaseous streamcan be recycled back to the desorber e.g., as indicated in FIG. 3 , foruse as a carrier gas or to further adsorb terpenes using sorbent in thedesorber (e.g., in the secondary adsorber section 213).

In certain embodiments, the condenser cooling liquid can optionally berecycled via a tempering pump to increase the heat removal efficiency ofthe condenser. The flow of cooling liquid and the amount that isrecycled and/or removed can be controlled, for example and notlimitation, by a pair of control valves based on the outlet temperatureof the stripped gaseous stream.

5.2.6 Sorbent Reactivation

Over time, sorbent can become blocked from adsorbing efficiently due tobuildup within pores or on the surface of the sorbent. Thus, thepresently disclosed system can further include a sorbent reactivationsystem. Using the sorbent reactivation system, sorbent can be removedfrom the adsorber and cleaned. In certain embodiments, the sorbent canbe stored in a load and/or storage hopper prior to reactivation. Thesorbent reactivation system can be operated continuously, or in batch orsemi-batch mode. For example, in particular embodiments, sorbentreactivation can take place continuously, such that a small side streamof sorbent is treated while the system is operating, i.e., in a sidestream reactivator. In certain embodiments, the sorbent reactivationsystem can comprise at least one desorber, coupled with and arrangeddownstream of the adsorption system. In some embodiments, the sorbentreactivation system can comprise a desorber and at least one side streamreactivator unit.

Spent or used sorbent that is no longer efficiently adsorbing compoundsin the adsorber can be directed to the desorber for treatment to removeand separate buildup within pores or on the surface of the sorbent. Inaddition to the desorber, some embodiments of the present disclosurealso provide and maintain an amount of reactivated spent sorbent to theadsorber via a side stream reactivator (SSR). Such a sorbentreactivation system comprising a side stream reactivator is particularlybeneficial when sorbent needs to be reactivated continuously for ongoingoperations. As disclosed herein, benefits and advantages of a sidestream reactivator include, but are not limited to, a continuous steadysupply of reactivated sorbent to the adsorber, a reduction in the amountof fresh (i.e., virgin) sorbent needed for the adsorption system,management of particulate buildup on adsorber trays and plugging ofdowncomers, and an ability to monitor and maintain sorbent apparentdensity at a preferred and/or operationally desirable value. Further, bymaintaining a certain sorbent apparent density, it is possible tocontrol emissions of and particulate matter within a wood dryer exhauststream as desired to be in compliance with environmental regulationsand/or environmental requirements.

The presently disclosed subject matter has found that by maintaining acertain sorbent apparent density, the side stream reactivator can helpthe overall adsorption system achieve about 100% reduction efficiency,or at least about 99% reduction efficiency, or at least about 98%reduction efficiency, or at least about 97% reduction efficiency, or atleast about 96% reduction efficiency, or at least about 95% reductionefficiency, or at least about 94% reduction efficiency, or at leastabout 93% reduction efficiency, or at least about 92% reductionefficiency, or at least about 91% reduction efficiency, or at leastabout 90% reduction efficiency of emissions from the exhaust stream atthe adsorber inlet.

In certain embodiments, the side stream reactivator can providereactivated sorbent at a rate between about 0.05% per day to about 10%per day, or between about 0.1% per day to about 10% per day, or betweenabout 0.5% to about 10% per day, or between about 1% to about 10% perday, or between about 5% per day to about 8% per day. In certainembodiments, the side stream reactor can provide reactivated sorbent ata rate of about 6% per day, or at a rate of about 5% per day, or at arate of about 4% per day, or at a rate of about 3% per day, or at a rateof about 2% per day, or at a rate of about 1% per day, or at a rate ofabout 0.9% per day, or at a rate of about 0.8% per day, or at a rate ofabout 0.7% per day, or at a rate of about 0.6% per day, or at a rate ofabout 0.5% per day, or at a rate of about 0.4% per day, or at a rate ofabout 0.3% per day, or at a rate of about 0.2% per day, or at a rate ofabout 0.1% per day, or at a rate of about 0.05% per day based on sorbentflow to the adsorber.

As an alternative to sorbent reactivation via the sorbent reactivationsystem as presently disclosed, virgin sorbent can be continuouslyintroduced into the adsorption system at a rate of about 6% per day, orat a rate of about 5% per day, or at a rate of about 4% per day, or at arate of about 3% per day, or at a rate of about 2% per day, or at a rateof about 1% per day, or at a rate of about 0.9% per day, or at a rate ofabout 0.8% per day, or at a rate of about 0.7% per day, or at a rate ofabout 0.6% per day, or at a rate of about 0.5% per day, or at a rate ofabout 0.4% per day, or at a rate of about 0.3% per day, or at a rate ofabout 0.2% per day, or at a rate of about 0.1% per day, or at a rate ofabout 0.05% per day based on sorbent flow to the adsorber.

As embodied herein, the sorbent can be reactivated using any suitablephysical and/or chemical techniques. For example, sorbent can bereactivated (i.e., cleaned) by heating to thermally decompose organics,using a high velocity impact to release particulate matter. For furtherexample, in particular embodiments, a side stream reactivator can heatsorbent between about 1000° F. to about 1600° F., or between about 1000°F. to about 1400° F., or between about 1400° F. to about 1600° F., orbetween about 1100° F. to about 1200° F., or between about 1400° F. toabout 1500° F., or between about 1450° F. to about 1500° F. Inparticular embodiments, the side stream reactivator can heat sorbent toabout 1000° F., about 1100° F., about 1200° F., about 1300° F., about1400° F., about 1450° F., about 1500° F., or about 1600° F. In certainembodiments, the side stream reactivator can heat sorbet to at leastabout 1400° F., at least about 1450° F., at least about 1500° F., or atleast about 1600° F. The side stream reactivator heats sorbent innitrogen in the presence of water to clean organics from the sorbent bythermally destroying them and using the water and/or superheated steamto assist with the cleaning. An amount of water used can be from about1% w/w to about 20% w/w, or about 1% w/w to about 10% w/w, or about 1%w/w to about 5% w/w, or about 10% w/w to about 20% w/w, or about 5% w/wto about 10 w/w %, on the basis of water to sorbent (e.g., carbon) beingtreated. In particular embodiments, an amount of water used can be about1% w/w, about 5% w/w, about 10% w/w, about 15% w/w, or about 20% w/w,basis of water to sorbet (e.g., carbon) being used. The system canfurther include a capture system, such as a cyclone or wet scrubber, bagfilter, wet electrostatic precipitator, or the like, to collectparticulate matter. Alternatively, particulate matter can be combusted,e.g., in a burning boiler with any unburned particulate filtered fromthe boiler exhaust.

Additionally or alternatively, the sorbent can be chemically treatedwith water (e.g., steam), super critical carbon dioxide, and/or causticsolution. In certain embodiments, a non-oxygen atmosphere can be used tocreate pyrolysis on the sorbent or a solvent extraction system can beused for sorbent reactivation.

When the sorbent is chemically treated, it can be desorbed in a bed,such as but not limited to in a fixed bed, fluidized bed, or packedmoving bed. In certain embodiments, the residence time of the sorbentwithin the bed of the adsorber can range from about 0.5 hours to about 4hours. In certain embodiments, the sorbent can be used in the systemwith at least about 6 months, or at least about 1 year, betweenreactivations.

5.2.7 Additional Components

The systems of the present disclosure can further include othercomponents and accessories, as known in the art.

For example, the presently disclosed systems can further includefeatures to facilitate cleaning and maintenance. For example, accesspanels can be provided within one or more components, such as the wooddryer, the air treatment box, the adsorber, the desorber, the condenser,separator pots, the side stream reactivator (SSR), etc. for cleaning andmaintenance. Additionally, lids, site glasses, covers, etc. can beprovided within one or more components of the systems of the presentdisclosure.

Additionally, components can be situated within or downstream from thedesorber to capture particulate matter. Such components can capturedesorbed particulate matter and/or inorganic compounds, such as metals,that are not desorbed from the sorbent. For example, in certainembodiments, a cyclonic separator can be used to capture downstreamparticulate matter. For further example, a liquid stream side phaseseparation can also be used to capture particulate matter, alone or incombination with a clarifier, centrifuge, or filtration system.

As embodied herein, heat can be recovered from the desorber and used topreheat another stream. For example, the gaseous stream exiting thedesorber can provide hot fluid for an economizer or heat exchanger thatheats a stream entering an upstream adsorber or the stream containingspent sorbent that enters to the desorber.

In certain embodiments, a decanter can be used for oil/water phaseseparation of recovered terpenes and water. Additionally oralternatively, a rag layer of the recovered material can be floated orskimmed off, or chemically separated using one or more separationagents.

As embodied herein, the system can further include one or more bleed offvalves or other release mechanisms for purging non-condensable gasesfrom the system. Such non-condensable gases can accrue in the systemover time, and under certain circumstances, will not be removed with theterpene stream. Thus, a bleed off valve or other release mechanism canbe periodically triggered, automatically or manually, to removenon-condensable gases. The bleed off valve or other release mechanismcan be positioned within the desorber or downstream from the desorber.Non-condensable components can include, but are not limited to, air andcarbon dioxide, carbon monoxide, and certain low molecular weight HAPs.In certain embodiments, a purge system can be coupled to a burner, e.g.,the burner used during drying operations, for removing and destroyingsuch non-condensable components. Additionally or alternatively, aportion of the stripped gaseous stream from the condenser (which wouldcontain the non-condensable gases) can be recycled to the adsorber andpurged from the system with the exhaust stream exiting the adsorber.

Furthermore, as embodied herein, the systems can include one or morecomponents for incinerating desorbed material, e.g., an incinerator,oven, kiln, flare, etc. For example, in certain embodiments, the gaseousstream from the desorber can be incinerated in its gaseous form (i.e.,without being condensed first). Alternatively, a condensed terpenestream can be incinerated.

In certain embodiments, the presently disclosed system can furtherinclude features to facilitate in its cleaning and maintenance. Forexample, access panels and spray nozzles for introducing water and/ordetergent solutions can be provided within the desorber to provideaccess to the bed(s) for cleaning and maintenance. Cleaning solutionsexist in the art and within the field of the presently disclosed subjectmatter. For example and not limitation, cleaning solutions of thepresent disclosure can include trisodium phosphate, sodium hydroxide,potassium hydroxide, ammonium hydroxide, calcium hydroxide, magnesiumhydroxide, Panel Bright, or the like.

In a non-limiting example of a scheduled cleaning, the equipment in needof cleaning is cooled. Any materials inside the equipment (e.g.,sorbent) is emptied and/or removed by, for example, draining through anoutlet nozzle of the equipment. Such removed materials can be collectedinto a container or filter bag as appropriate. The emptied sorbent canbe stored in vessels (e.g., pails or drums) or alternatively transportedto a load hopper via the eductor, airlift system, and separator pots.Sorbent can be additionally cleaned from the equipment in need ofcleaning by brushing the equipment. The equipment in need of cleaning isisolated from upstream and downstream equipment through the close andlock of appropriate valves. The equipment internals are first rinsedwith fresh water, for example, via manual water deluge located at thetop of the equipment. A cleaning solution, such as, but not limited to,trisodium phosphate or Panel Bright is applied to the internals forapproximately 30 minutes. The equipment is then rinsed again with freshwater to remove cleaning solution. An operator can perform a visualinspection of the equipment internals via sight glasses and determinewhether the surfaces and/or undersides of the equipment internals havebeen cleaned. Multiple cycles of cleaning and rinsing with fresh watercan be employed. When cleaning and rinsing is complete, the equipmentcan be connected to process fan(s) and/or airlift fan(s) as presentlydisclosed for drying. After the equipment is clean and dried, saidequipment can be reconnected with upstream and downstream equipment viacontrol and/or isolation valves. Materials can be reloaded into theequipment for start-up.

Various process controls can be used to ensure the safety and efficiencyof the system. The process controls can be based on read outs fromvarious measurement features, and can optionally be automaticallytriggered by certain threshold measurements. These process controlfeatures can include any suitable measurement or other process controlaccessory known in the art including, but not limited to, pressureindicators, pressure transmitters, pressure regulators, differentialpressure cells, thermowells, temperature indicators, thermocouples,temperature switches, resistance temperature detectors, pH meters, flowmeters, mass meters, turbine meters, flow monitors, flow regulators andvalves, gas analyzers, LEL monitor, oxygen analyzer, humidity sensors,radar sensors, hopper level probes, ammeters, current meters, liquidlevel and level interface detectors (e.g., in a terpene collectionsystem), photon ionization detectors (PID), solenoids, and/or drives(e.g., electrical drives). In certain embodiments, the process controlscan be implemented using a programmable logic controller (PLC) and/orDCS system with both on and off-site access capability. Process controlsinclude, but are not limited to, water deluge to extinguish fires,system shut downs, or heater shut downs, etc. For example, in theadsorber, sensors can be used to trigger water deluge to extinguishfires.

In particular embodiments, process controls can include in-line oxygenanalyzers to monitor oxygen levels within the desorber. The system canfurther include one or more safety interlocks based on oxygen levelsand/or temperature to intervene if the process conditions have anincreased chance of auto-ignition or deflagration. For example, incertain embodiments, an oxygen analyzer can be coupled with a PLC. ThePLC can send an alarm if the oxygen level rises above a set threshold,e.g., 2 wt-%. Additionally or alternatively, if the oxygen level risesabove a higher threshold, e.g., 5 wt-%, the PLC can shut down the entiresystem until oxygen levels return to an acceptable range.

5.3 Methods of Recovering Terpenes

The present disclosure further provides methods of recovering andcollecting target chemicals, compositions, or components thereof fromexhaust streams. In a specific embodiment, the present disclosureprovides methods of recovering terpenes from exhaust streams.Specifically, the exhaust streams can be derived from a wood dryingprocess. Thus, the methods can include providing an exhaust stream to anadsorber and contacting the exhaust stream with a sorbent within theadsorber to generate the spent sorbent containing adsorbed material,e.g., terpenes. In certain embodiments, the exhaust stream can bepre-treated prior to adsorption. For example, the exhaust stream can bephysically and/or chemically treated and, in particular, can be passedthrough one or more baffles, filters, screens, and/or perforated platesto remove particulate matter and other debris from the exhaust stream.Additionally or alternatively, the exhaust stream can be dehumidifiedand/or pre-heated prior to introduction to the adsorber. For example,and not limitation, the exhaust stream can be heated to reduce itsrelative humidity downstream from the dryer, but upstream from theadsorber.

Adsorption can occur when the exhaust stream is contact with thesorbent, which can adsorb one or more components from the exhauststream. For example, and not limitation, the sorbent can adsorb VOCs,such as terpenes, HAPs (such as formaldehyde, methanol, phenol,acrolein, acetaldehyde, and/or propionaldehyde), and/or particulatematter, such as PM 2.5 particulate matter from the exhaust stream.

As discussed below, the present disclosure provides for the desorptionof materials or chemicals adsorbed by the sorbents. As noted above, suchmaterials can include targeted chemicals, such as terpenes.

5.3.1 Methods of Desorption

As embodied herein, the desorption can be carried out using a number ofdifferent techniques. For example, in certain embodiments, materials canbe desorbed from the sorbent in nitrogen or another inert gas viathermal desorption. For example and not limitation, thermal energy canbe provided via electric immersion heaters or thermal oil.Advantageously, thermal oil can minimize temperature variation. However,desorption can occur through various other mechanisms, includingsupercritical CO₂ desorption, solvent extraction, and steam stripping.

Following desorption, a gaseous terpene stream can be obtained from thedesorber. This gaseous stream can contain desorbed terpenes, along withother desorbed materials, carried by the inert carrier gas. The terpenesand other desorbed materials can be in gaseous form, or alternatively,can be carried as small liquid droplets or solid particulates. Inaddition to terpenes, the desorbed materials can include other VOCs,HAPs (such as formaldehyde, methanol, phenol, acrolein, acetaldehyde,acetic acid, and/or propionaldehyde), other condensable compounds, andparticulate matter, such as PM 2.5, PM 10, fatty acids, and fineparticulate. In certain embodiments, the gaseous stream can beincinerated to destroy these desorbed materials such that terpenes arenot recovered for downstream use.

However, in certain embodiments, the presently disclosed methods canfurther include recovering terpenes from the gaseous stream. In certainembodiments, other compounds, e.g., HAPs, condensable compounds, andparticulate matter, can be recovered from the gaseous stream along withthe terpenes. Alternatively, in certain embodiments, the gaseous streamcan undergo additional separations to remove one or more of thesecomponents before or after condensation of terpenes from the gaseousstream. In particular embodiments, HAPs, such as formaldehyde, methanol,phenol, acrolein, acetaldehyde, and/or propionaldehyde, can beseparately recovered from the gaseous stream, such that they areseparated from the terpenes and suitable for downstream use. Forexample, multiple condensers operating at different temperatures can beused to selectively remove HAPs before or after condensing terpenes. Incertain embodiments, HAPs and other water-soluble emissions (e.g.,formaldehyde, methanol, or acetic acid) can be collected in an aqueousportion of condensate as to be at least partially separated fromterpenes in systems and methods of the present disclosure. Additionally,and as noted above, layers of condensed water, terpenes, and organicfractions can be advantageously separated using a decanter.

Thus, the presently disclosed methods and systems can be used to recovera terpene stream. As embodied herein, the terpene stream can containalpha-pinene and/or beta-pinene. For further example, and notlimitation, the terpene stream can contain other terpenes such ascamphene, fenchene, alpha-fenchene, limonene, o-cymene, p-cymene,alpha-terpineol, cis-beta-terpineol, trans-beta-terpineol,gamma-terpineol, p-allylanisole, tricyclene, p-xylene, vinylcyclohexen,2-norpinene, terpilene, p-cymenene, fenchol, myrcene, terpinolene,cis-anethole, trans-anethole, caryophyellenes, alpha-phellandrene,beta-phellandrene, methyl chavicol, tricyclene, 1,4-cineole,1,8-cineole, 3-carene, alpha-terpinene, gamma-terpinene, isoterpinolene,camphor, L-camphor, isoborneol, borneol, L-borneol, cis-1,8-terpin, andtrans-1,8-terpin, camphenilone, fenchone, exo-fenchol,exo-2,7,7-trimethylbicyclo[2.2.1]heptan-2-ol, fenchyl acetate, borneolacetate, among others.

The recovered terpene stream can comprise from about 0 wt-% to about 100wt-% alpha-pinene, or from about 1 wt-% to about 100 wt-% alpha-pinene,or from about 1 wt-% to about 50 wt-% alpha-pinene, or from about 1 wt-%to about 40 wt-% alpha-pinene, or from about 1 wt-% to about 30 wt-%alpha-pinene, or from about 1 wt-% to about 20 wt-% alpha-pinene, orfrom about 1 wt-% to about 10 wt-% alpha-pinene. Additionally oralternatively, the terpene stream can comprise from about 0 wt-% toabout 50 wt-% beta-pinene, or from about 0 wt-% to about 40 wt-%beta-pinene, or from about 0 wt-% to about 30 wt-% beta-pinene, or fromabout 0 wt-% to about 20 wt-% beta-pinene, or from about 0 wt-% to about10 wt-% beta-pinene.

As demonstrated in the Examples, it has been found that increased timeand temperature within the desorber can lead to the thermalrearrangement of terpenes. For example, when alpha- and beta-pinenes aresubjected to heat at higher temperatures and longer time periods, theycan rearrange to dipentene (e.g., limonene), and camphene. Additionally,reducing the temperature of the desorber can decrease the likelihood ofauto-ignition and improve the overall safety of the presently disclosedsystem and methods. Accordingly, in certain embodiments, the presentlydisclosed methods can include controlling the conditions of desorption,such as but not limited to temperature, to enhance the recovery ofalpha-pinene and/or beta-pinene.

For example, in certain embodiments, the residence time of the terpeneswithin the desorber, i.e., the time period from when the spent sorbententers the desorber with adsorbed terpenes to the time the releasedgaseous stream exits the desorber, is minimized. In certain embodiments,the total time the sorbent spends in the desorber can range from about30 minutes to about 100 minutes, about 30 minutes to about 20 hours,from about 45 minutes to about 15 hours, from about 1 hour to about 12hours, from about 2 hours to about 10 hours, from about 2 hours to about8 hours, or from about 2 hours to about 6 hours. In particularembodiments, the sorbent can spend a total time of about 2.8 hours,about 7.5 hours, or about 10 hours in the desorber. In certainembodiments, the sorbent can spend a total time of at least about 30minutes, at least about 1 hour, at least about 5 hours, or at leastabout 10 hours in the desorber.

In certain embodiments, the residence time in the heated section of thedesorber can be less than about 4 hours, or less than about 3 hours, orless than about 2.5 hours, or less than about 2 hours, or less thanabout 1.75 hours, or less than about 1.5 hours, or less than about 1.25hours, or less than about 1 hour, or less than about 45 minutes, or lessthan about 30 minutes, or less than about 15 minutes. For example andnot by limitation, the time sorbent spends in the heated section of thedesorber can be from about 15 minutes to about 4 hours, from about 20minutes to about 3 hours, from about 25 minutes to about 2.5 hours, fromabout 30 minutes to about 2 hours, from about 30 minutes to about 1.75hours, from about 30 minutes to about 1.5 hours, from about 30 minutesto about 1.25 hours, or from about 30 minutes to about 1 hour.Additionally, the temperature of desorption can be maintained within setthresholds.

For example, and not limitation, the temperature can be maintained atless than about 750° F., or less than about 700° F., or less than about650° F., or less than about 600° F., or less than about 550° F., or lessthan about 500° F., or less than about 450° F., or less than about 400°F., or less than about 350° F. throughout desorption. In particularembodiments, the temperature can be maintained within a range of fromabout 300° F. to about 550° F., or from about 320° F. to about 530° F.,or from about 350° F. to about 450° F., or from about 370° F. to about430° F., or from about 390° F. to about 430° F.

Furthermore, in certain embodiments, the flow of the inert carrier gasduring desorption can be modulated to control terpene composition. Forexample, higher gas flow rates can entrain sorbent and tend to move itduring desorption, whereas lower flow rates can reduce the effectivenessof terpene removal from sorbent because organics can be desorbed, thenre-adsorbed instead of being carried by the gaseous stream. In certainembodiments, the linear velocity or superficial flow velocity within thedesorber can range from about 1 linear foot per minute to about 20linear feet per minute, or from about 10 linear feet per minute to about20 linear feet per minute, or from about 2 linear feet per minute toabout 18 linear feet per minute, or from about 5 linear feet per minuteto about 15 linear feet per minute, or about 8 linear feet per minute toabout 10 linear feet per minute of gaseous flow. In particularembodiments, the linear velocity or superficial flow velocity within thedesorber can be about 10 linear feet per minute, about 15 linear feetper minute, about 18 linear feet per minute, or about 18 linear feet perminute. In some embodiments, inert gas can be recycled to the desorberat a rate of between about 1 cfm to about 20 cfm, or between about 2 cfmto about 18 cfm, or between about 3 cfm to about 16 cfm, or betweenabout 4 cfm to about 14 cfm, or between about 5 cfm to about 12 cfm, orbetween about 6 cfm to about 10 cfm, or between about 7 cfm to about 9cfm, or about 8 cfm. In certain embodiments, inert gas can be recycledto the desorber at a rate of between about 8 cfm to about 12 cfm orbetween about 8 cfm to about 9 cfm. In particular embodiments, inert gascan be recycled to the desorber at a rate of about 8 cfm, about 8.5 cfm,about 9 cfm, or about 12 cfm.

When the residence time, temperature, and/or velocity and/or otherprocess parameters are maintained as disclosed herein, the recoveredterpenes can have increased alpha-pinene and beta-pinene content ascompared to a terpene stream in which thermal rearrangement hasoccurred. In such embodiments, the desorbed terpenes in a condensedterpene stream can include a certain amount of alpha-pinene andbeta-pinene, based on the total weight of terpenes in the recoveredgaseous stream. For example, the collective amount of alpha-pinene andbeta-pinene in the terpene stream can range from about 15 wt-% to about100 wt-%, or from about 20 wt-% to about 99 wt-%, or from about 25 wt-%to about 95 wt-%, or from about 30 wt-% to about 90 wt-%, or from about50 wt-% to about 100 wt-%, or from about 50 wt-% to about 99 wt-%, orfrom about 50 wt-% to about 97 wt-%, or from about 50 wt-% to about 95wt-%, or from about 50 wt-% to about 90 wt-%. For example, in certainembodiments, the amount of alpha-pinene in the terpene stream can rangefrom about 20 wt-% to about 97 wt-%, or from about 30 wt-% to about 97wt-%, or from about 40 wt-% to about 97 wt-%, or from about 45 wt-% toabout 97 wt-%. In particular embodiments, the amount of alpha-pinene inthe terpene stream can range from about 31 wt-% to about 35 wt-%.Additionally or alternatively, the amount of beta-pinene in the terpenestream can range from about 5 wt-% to about 60 wt-%, or from about 10wt-% to about 60 wt-%. In particular embodiments, the amount ofbeta-pinene in the terpene steam can range from about 13 wt-% to about17 wt-%.

Additionally, in certain embodiments, the terpene stream can includeless than about 15 wt-%, less than about 10 wt-%, or less than about 5wt-% dipentene (e.g., limonene), e.g., from about 0 wt-% to about 20wt-% dipentene. Additionally or alternatively, the terpene stream caninclude less than about 15 wt-%, less than about 10 wt-%, or less thanabout 5 wt-% camphene, e.g., from about 0 wt-% to about 15 wt-%camphene.

In certain embodiments, the recovered terpenes can be further purifiedand/or isolated using any suitable means as known in the art. Forexample, and not limitation, terpenes can be purified using thermalfractionation, chemical separation, liquid-liquid extraction,distillation, stripping, decanting, and/or further adsorption anddesorption. In certain embodiments, the further purification can involveone or more chemical reactions, e.g., facilitated by a catalyst.

5.4 Benefits and Advantages

Thus, the systems and methods of the present disclosure provide forimproved terpene compositions from wood drying processes, and can havenumerous advantages. These terpene compositions having increasedalpha-pinene and beta-pinene content can have similar or improvedalpha-pinene and beta-pinene content as compared to naturally-sourcedturpentine, e.g., turpentine distilled from wood resins such a crudesulfate turpentine (CST). Turpentine distilled from wood resinsgenerally includes up to about 85 wt-% alpha-pinene, with smalleramounts of beta-pinene, e.g. up to about 30 wt-%. Turpentine alsogenerally includes less than 15 wt-% of each of camphene and limonene,and other terpenes such as myrcene, terpinolene, alpha-terpineol,cis-anethole, trans-anethole, carophyellenes, beta-phellanderene, methylchavicol, 3-carene, and the like. For example, turpentine can include upto about 15 wt-%, or up to about 10 wt-% dipentene. Distilled turpentinecan further include pine oil and residual wood resins.

The presently disclosed terpene compositions can have similar combinedamounts of alpha-pinene and beta-pinene to such turpentine distilledfrom wood resins, which can make them suitable for similar applications,including for use in the fragrance and flavor industry, which typicallyrequires relatively large amounts of these higher value terpenes. Theterpene compositions can also be used in other industries, including asfuel or solvents, e.g., for paints and varnishes or for oilfield (e.g.,Enhanced Oil Recovery or EOR) applications, or terpene compositions canbe used in adhesive resins or traditional medicines (e.g., traditionalChinese medicines). Additionally, and as compared to turpentine,particularly turpentine obtained from the digestion of wood productssuch as crude sulphate turpentine (CST), the presently disclosed terpenecompositions can be free of sulfur, as there is no sulfur present in theadsorbed materials or the recovered terpene stream.

Additionally, desorption according to the presently disclosed subjectmatter can have advantages as compared to other possible methods ofseparating terpenes from wood drying exhaust. For example, althoughliquid-liquid extraction can remove terpenes from exhaust, extractorsare generally energy-intensive and require a large of amount of space.Additionally, extractors consume large amounts of solvent that must besupplied, regenerated, and disposed of. In contrast, desorption(particularly thermal desorption) in accordance with the presentlydisclosed subject matter can recover terpenes from a sorbent and can bereleased or recycled without further purification once the recoveredterpenes are condensed or otherwise removed from the gaseous stream.Furthermore, steam desorption of sorbent could be utilized, however,such processes increase the amount of water generated and thereforerequire an outlet.

EXAMPLES

The following examples are merely illustrative of the presentlydisclosed subject matter; they should not be considered as limiting thescope of the subject matter in any way.

Example 1: Adsorption Trials with Fully Fluidized Fresh Beads

This Example describes a trial performed with full trays and fullyfluidized beads using a process exhaust stream from a wood dryingprocess, simulating an adsorption batch process.

About 300 cfm of an exhaust stream from a wood drying process wasdiverted to an air pre-treatment box using a process fan. The airpre-treatment box was configured to reduce particulate matter of thedryer exhaust. The discharge of the process fan had two balancingdampers to control the flow of the gaseous stream to activated carbonbeads. The trial was run as the wood drying process was coming online.In the early stages of the process, 2 of the 5 dryers were running inthe wood drying process, however, by about 2 hours into the trial, 4 ofthe 5 dryers were running.

During the trial, it took about 2 hours for the fluidized bed to warm toprocess air temperature. A schematic illustration of the fluidized bedused in the present example is provided in FIG. 4 . As the process beganto stabilize, after about 2 hours, the trays 109 equipped with weirs 110began to fill and fluidize. The bead transport rate was increased fromabout 150 lb/hr to about 200 lb/hr to fully fill and fluidize beadswithin the trays. By 3 hours, the process was stabilized with the traysfull and fluidized.

Once stable, the bed temperature averaged from about 150° F. to about160° F., except the top tray, which was at about 135° F. throughout thetrial. Small air flow adjusters, approximately 3.5″×15″, were weightedfor stabilization and positioned in the downcomer trays to facilitatetray filling, fluidization, and overflow to the downcomer trays. Basedon pitot tube measurements, the calculated air flow within the fluidizedbed was 294 cubic feet per minute (cfm).

Impingers containing 15 mL acetonitrile were set up both before (Inlet)and after (Outlet) the bed to collect emissions. System air was bubbledthrough impinger solutions via fitted spargers at about 50 mL/min viapressure provided from the fluidized bed. The pressure at the inlet ofthe bed was approximately 5-6 inches of water whereas the pressure atthe outlet of the bed was approximately 3-4 inches of water.

Bead Attrition

Attrition of the beads within the fluidized bed was observed using SEMmicroscopy. FIGS. 5A-5B provide images of new and used beads,respectively, at 50× magnification. The mechanical impact on the beadswas studied to determine whether there was bead deterioration during thetrial, which lasted about 6 hours.

Upon visual inspection of the SEM images, cracks were noted in both newand used beads and overall, there was no gross difference between thetwo sets of beads. This result indicates that the beads used in theExample are sufficiently robust to be used in the fluidized bedadsorption process with minimal attrition.

Bead Adsorption

The adsorption onto the beads was studied at various time points in thetrial. The density of the beads was measured and thermal gravimetricanalysis (TGA) was performed to determine the percentage of bead weightattributable to adsorbed organics. The beads were found to containapproximately 5% organics, mainly terpenes, and 3% water. The full datais presented in Table 1 and provided in FIG. 6 , which shows beaddensity and percentage organics as a function of time. However, asdescribed in further Examples, sorbent in a commercial system couldinclude less water and more organics, depending in part on the startupconditions of the adsorber and the hydrophobicity of the sorbent.

TABLE 1 Elapsed Time Bead Density TGA-IR (min) Notes (g/mL) % Organics 0Start air flow to warm bed 0.584 0.00% 120 Load beads & start impingers— — 180 Process Stabilized 0.603 0.82% 240 Process Stable 0.600 2.60%300 Process Stable 0.611 3.93% 360 Process Stable 0.618 5.10% 420Process Stable 0.630 6.06% 480 Process Stable/Shutdown 0.633 6.40%

Emissions at Impingers

As noted above, samples were taken at two impingers located at the inletand outlet of the fluidized bed. Samples were taken over different timeperiods ranging from 2 to 8 hours, with the results as shown in Table 2,below.

TABLE 2 Elapsed MeOH (ppm) HCHO (μg/mL) β-Pinene (ppm) α-Pinene (ppm)Time (min) Inlet Outlet Inlet Outlet Inlet Outlet Inlet Outlet 120 ND ND0.8 0.1 NQ NQ 41.8 NQ 180 ND ND 0.8 0.2 NQ ND 41.8 ND 240 ND ND 0.2 0.2NQ ND 47.2 ND 300 ND ND 0.2 0.2 NQ ND 47.2 ND 360 ND ND 0.2 0.2 NQ ND39.5 ND 420 ND ND 0.2 0.2 NQ ND 39.5 ND “ND” means non-detectable and“NQ” means non-quantifiable.

As shown in Table 2, there were no detectable methanol (MeOH) emissionsat either the inlet or the outlet during any collection time period.Formaldehyde (HCHO) emissions were approximately the same at both theinlet and outlet, particularly once the process was stable. The outletformaldehyde emissions in samples taken after 2 hours (120 min) wereabout half the amount in samples taken after 3 hours (180 min).Alpha-pinene emissions were higher at the bed inlet than the bed outlet.In particular, at the outlet impinger, alpha-pinene results werenon-quantifiable (NQ), but detectable at 2 hours, during which time thebeads did not fill the trays. Similarly, beta-pinene emissions werenon-quantifiable but detectable at the inlet, but not detectable (ND) atthe outlet, except at 2 hours, during which time the beads did not fillthe trays. These results indicate that when there are fewer collisions(i.e., less air contact) with the beads, emissions are reduced to alesser degree. Overall, the amount of terpenes, e.g., alpha- andbeta-pinene, and other organics was reduced after passing through thefluidized bed, indicating that the activated carbon beads successfullyadsorbed a portion of these VOCs.

In sum, this Example shows that good bead flow and fluidization can beobtained using systems in accordance with the disclosed subject matter.Bead flow can be controlled by adjusting eductor height, airlift fanspeed/pressure, orifice to modulate airflow through adsorber, andinlet/outlet pressures at the fluidized bed. The beads adsorbed organicslinearly over the run time (FIG. 6 ). Additionally, the initialqualitative impinger analyses indicate that terpenes emissions aresignificantly reduced by adsorption onto activated carbon beads influidized bed.

Example 2: Pilot Scale Fluidized Bed for Adsorbing VOCs from an ExhaustStream

This Example describes pilot scale testing of a system for removing VOCsfrom the exhaust stream of a wood drying process in accordance with thedisclosed subject matter.

A process fan was configured to pull a slip stream of approximately 300cfm from the exhaust stream of a wood drying process through an airpre-treatment box including a perforated plate, 100 mesh screen, andpleated filter to reduce particulate matter of the dryer exhaust. Thedischarge of the process fan had two balancing dampers to control theflow to a fluidized bed containing activated carbon beads atapproximately 300 cfm, such that excess exhaust bypassed the bed toachieve optimum fluidization. These pilot trials were operated insemi-batch mode. A continuous process was operated through the adsorberand the desorber was operated in a batch process. Table 3 provides theparameters of the process fan and fluidized bed.

TABLE 3 Process fan suction −10 to −15 inches of water Inlet pressure(upstream of discharge 4 to 11 inches of water bypass line) Fluidizedbed after inlet diffuser 5 to 12 inches of water Fluidized beddifferential pressure (out-in) 2 to 4 inches of water Fluidized bedoutlet pressure 1.5 to 4 inches of water Temperature before airpre-treatment box 164° F. to 178° F. Temperature at process fandischarge 164° F. to 180° F. Temperature at bottom of bed (hopper) 117°F. to 164° F. Temperature at bottom tray of bed 136° F. to 170° F.Temperature at middle tray of bed 136° F. to 168° F. Temperature at toptray of bed 122° F. to 146° F. Outlet temperature 130° F. to 158° F.Bead transport rate 100 to 205 pounds per hour Air flow (actual) 250 to325 cfm Air flow (dry standard) 175 to 250 dscfm Air flow (standard) 225to 300 scfm

Over a period of 38 hours, samples were taken on an hourly basis for twotrial runs. The following measurements were taken: bead density,percentage weight gain of the beads, ppm of hydrocarbons at inlet andoutlet as measured by a flame ionization detector (FID), and thepercentage water and organics as measured by thermal gravimetricanalysis (TGA).

Bead Adsorption

FIG. 7A shows the bead density over time for each trial. As shown inFIG. 7A, bead adsorption generally increased with time in a linearfashion. FIG. 7A further shows the ppm of hydrocarbons at the outlet ofthe fluidized bed. The amount of hydrocarbons generally increased withtime exponentially, presumably at the beads began to reach capacity. Thetrials had good replication up to about 15 hours, over which time thebeads adsorbed a generally stable amount of hydrocarbons.

FIG. 7B provides the results of the thermal gravimetric analysis,comparing the percentage of organics (terpenes) and water with the runtime. In the top panel of FIG. 7B, the percentage organics is overlaidwith bead density showing that the percentage organics generally trackedbead density for each of the two runs. The maximum percentage organicsadsorbed for both runs was approximately 22.5%. As shown in the bottompanel of FIG. 7B, the amount of water versus total adsorbed ranged from1 to 20%, but up to about 10% water was typical. The total adsorbedamount is based on the total weight loss of the sorbent when heated to600° F., when measured by thermal gravimetric analysis. Adsorption ofhigher levels of water was seen on bead samples with shorter run times,possibly due to adsorption of condensed water early in runs.

FIG. 7C provides the terpenes yield, extrapolated over a year as afunction of run time assuming a wood drying product of about 300,000 drytons per year. As shown in FIG. 7C, terpenes yield decreased based onrun time, but generally remained over 200,000 gallons of terpenes peryear. Additionally, terpene yield was estimated based on wood dryingproduction of about 300,000 dry tons per year, assuming a terpenes yieldof 1.16 gallons per dried ton (Naval Stores Reference Guide, p. 189) andan efficiency yield of 75%, resulting in an estimated about 260,000gallons of terpenes per year. Thus, the terpenes yield extrapolated fromestimated bead adsorption generally matches the calculated terpenesyield. Although FIG. 7C shows a reduction in terpenes yield versus time,under the operating conditions of continuous adsorption coupled to adesorber and condenser, the terpenes yield would be expected to beconstant over time.

FIG. 7D shows thermal gravimetric analysis results, when the analysiswas performed isothermally. A sample of beads taken at 29 hours wasanalyzed. The beads were heated at 77° F. per minute to various holdtemperatures in separate experiments and maintained at each holdtemperature until weight loss stopped. The hold temperatures were 167°F., 212° F., 257° F. 302° F., 347° F., 392° F., 482° F., 572° F., and662° F. FIG. 7D shows weight loss over time for each hold temperature.As the temperature increased, the weight loss increased and the timenecessary to desorb materials generally decreased. At 662° F., thereappeared to be some degradation of the beads, indicating that thistemperature is too high to remove organics. Optimal desorptiontemperature is likely 302° F. to 932° F., or 302° F. to 662° F., withlower temperatures within that range preferred to minimize the heatenergy required for desorption and to maximize the alpha-pinene andbeta-pinene content in the desorbed stream.

Removal Efficiency

FIG. 7E compares the percentage reduction in VOCs (based on the FIDanalysis described above) and the percentage weight gain of the beads.FIG. 7E demonstrates that for both runs, the beads reduced the ppmorganics in the process exhaust by at least 90% (meeting the target forreduction) in the operating window, as specified by the MaximumAvailable Control Technology (MACT) requirement for plywood andcomposite wood products (PCWP), while the beads gained no more than 15%by weight.

FIG. 7F shows the air flow at the inlet and outlet of the fluidized bedin terms of Standard Cubic Feet per Minute (sCFM), Dry Standard CubicFeet per Minute (dsCFM), and Actual Cubic Feet per Minute (aCFM). Theair flow into and out of the fluidized bed were within 10% of eachother, indicating that the air exiting the bed was not significantlydiluted by the fresh air added to the bed by the airlift blower underthe process conditions. Accordingly, the observed reduction in VOCemissions was due to adsorption, since any VOC emissions in the airexiting the bed were undiluted.

FIG. 7G provides the percentage reduction in VOCs (based on emissionsdata at impingers located at the inlet and outlet of the fluidized bed)and the percentage weight gain of the beads. The emissions werecollected in two impingers in series containing 15 mL acetonitrile eachfor 120 minutes with approximately 1 liter/min process air flow. Thisemissions data from the impingers indicates that the terpenes are veryefficiently adsorbed by the beads, particularly within the operatingwindow. However, formaldehyde was less efficiently adsorbed by thebeads. Under the conditions of continuous adsorption coupled tocontinuous desorption and recovery, the VOC (including formaldehyde)reduction is expected to be constant with time, unlike the data shown inFIGS. 7E and 7G.

Bead Desorption

Based on the thermal gravimetric analysis under isothermal conditionsdescribed above, beads were desorbed at 572° F. for 55 minutes. Afterdesorption, the beads were subjected to further thermal gravimetricanalysis to determine the amount of organics remaining on the beadsfollowing desorption. The beads showed an initial 1.8% weight loss fromwater. Between 572° F. and 1382° F., there was an additional 1.3% weightloss from water, carbon dioxide, and a small amount of carbon monoxide.No organic compounds or particulates were identified in the off-gases.The apparent density of virgin beads was 0.602 g/mL and the apparentdensity of beads after desorption was 0.608 g/mL, whereas the apparentdensity of the beads after adsorption was 0.76 g/mL. Thus, the apparentdensity of the beads after desorption was nearly equal to that of thevirgin beads, indicating that only a very small percentage of the beadcapacity was irreversibly blocked at 572° F., well within the designspecifications for a fluidized bed adsorber. Moreover, the thermalgravimetric analysis of the beads after desorption showed only waterremaining on the beads, and no organic compounds or particulates. Theseresults indicate that the activated carbon beads of this Example can bevery efficiency desorbed.

Beads were also extracted by mixing with hexane, ethyl acetate, andacetonitrile at room temperature. The resulting solvent extracts wereanalyzed for terpenes content, then normalized and compared to terpenesdesorbed using thermal desorption. FIG. 7H provides a comparison of theterpenes yield. As shown in FIG. 7H, terpenes not exposed to heat haverelatively high alpha-pinene and beta-pinene content.

In sum, this Example demonstrates that bed fluidization was sufficientfor efficient adsorption onto activated carbon sorbent. Once stable,minimal operator intervention was required to maintain performance ofthe adsorber. Any potential water condensation issues were largelyaddressed by pre-warming the fluidized bed prior to bead introduction.Some condensation in the hopper caused the beads to stop flowingtemporarily, indicating that additional heat (e.g., a heat source,better insulation, etc.) for the hopper can be desirable to ensure thatthe operating temperature remains above the dewpoint and preventcondensation.

After running continuously for 36 hours, there was no significantoccurrence of particulate or tarry scale within the fluidized bed,although there was tarry scale build up on the perforated plate in theair pre-treatment box.

The maximum bead saturation was approximately 20-25% organics by weight.The amount of adsorbed water as compared to organics should not exceed10% when system comes to equilibrium in continuous runs to ensureefficient adsorption of organics. Emissions as measured by FlameIonization Detection (FID) indicated that the fluidized bed reduced theppm of organics in the process air by at least 90% when beads hadadsorbed less than or equal to 15% organics by weight. These densitymeasurements demonstrated that the beads were not saturated until afterthe beads had adsorbed about 15% of their initial weight, indicatingtheir high propensity for adsorption. This result demonstrates that thebeads can meet a very high adsorption efficiency.

Example 3: Operation of Fluidized Bed for Removal of Volatile OrganicCompounds

This Example describes pilot scale testing of a system for removingVOCs, such as terpenes, from the exhaust stream of a wood dryingprocess.

To test the capabilities for removing such VOCs, a process fan wasconfigured to draw a portion of exhaust of approximately 300 cfm from anexhaust stream from a wood dryer. The remaining exhaust stream waspassed to a conventional regenerative thermal oxidizer (RTO). Theportioned stream was passed through an air pre-treatment box to reduceparticulate matter. Two balancing dampers were used to control the flowfrom the process fan and air pre-treatment box. After pre-treatment, theportioned stream was passed to a fluidized bed adsorber containing beadactivated carbon (BAC) (from Kureha America, Inc.). The pilot system wasoperated in semi-batch mode to allow the BAC to adsorb pollutants,mainly VOCs.

The process parameters of the process fan and fluidized bed aresummarized in Table 4, below.

TABLE 4 Process fan suction −9 to −10 inches of water Inlet pressure(upstream of discharge 8 inches of water bypass line) Fluidized bedafter inlet diffuser 7 to 8 inches of water Fluidized bed differentialpressure (out-in) 2 to 3 inches of water Airlift fan discharge pressure20 to 35 inches of water Temperature before air pre-treatment box 160°F. to 175° F. Temperature at process fan discharge 165° F. to 180° F.Temperature at bottom of bed 145° F. to 160° F. Temperature at bottomtray of bed 155° F. to 170° F. Temperature at middle tray of bed 155° F.to 170° F. Temperature at top tray of bed 135° F. to 155° F. Outlettemperature 130° F. to 158° F. Bead mass transport rate 100 to 250pounds per hour Air flow (actual) 320 to 425 cfm Air flow (dry standard)225 to 300 dscfm

To determine the compositions of (1) the exhaust stream entering the airpre-treatment box (and subsequently, the fluidized bed), (2) the streamexiting the fluidized bed, and (3) the stream entering into the RTO,several tests were performed. The velocity, volumetric flow rate,moisture, and molar weight of each stream were determined according toEPA Methods 2, 3, and 4. Additionally, several measurements wereperformed to determine the amount of particulate matter in each stream.The total amount of filterable particulate matter was determinedaccording to EPA Method 5. The amount of filterable particulate matterhaving diameters less than 2.5 μm (PM 2.5) and less than 10 μm (PM 10)were measured using particle size analysis. The amount of condensableparticulate matter was measured using EPA Method 202.

The VOC loading of the streams entering and exiting the fluidized bedwere measured based on the gaseous streams. EPA Method 25A, without amethane cutter, was used to determine the amount of VOCs as totalhydrocarbons based on a propane calibration for the RTO. EPA Method 25A,adjusting for certain organic components (such as methanol andformaldehyde) according to Wood Products Protocol 1 (WPP1), was used todetermine a measure of VOCs for the fluidized bed system. The amount ofHAPs, notably methanol and formaldehyde, was also measured using NCASIMethod 98.01, which was performed with and without additional qualityassurance samples (e.g., sample runs with reagent blanks, duplicates,and various spikes).

HAPs Emissions

The fluidized bed system was observed to reduce HAPs emissions, as HAPswere adsorbed onto the activated carbon beads. For example, FIG. 8Ashows the percentage reduction in the HAPs methanol and formaldehydeover a 2.5 hour run time, as measured by impingers located at the inletand outlet of the fluidized bed. The emissions data from the impingersindicates that the beads adsorb formaldehyde and methanol, but that over2-3 hours, their ability to adsorb HAPs decreases.

Thus, the fluidized bed reduced HAPs emissions most effectively uponstartup when the beads had an apparent density of about 0.6. Over time,as the apparent density of the beads increased, their capability forHAPs adsorption decreased. This result suggests that recirculation ofbeads or otherwise maintaining a low apparent density via techniquessuch as thermal desorption can enable continuous desorption of the beadswhile effectively controlling HAPs.

Particulate Control

It was observed that the amount of particulate matter was reduced at theoutlet of the fluidized bed. To confirm that this was not due to asignificant reduction during stream pre-treatment that is notrepresentative of particulate reduction upstream from convention RTOs,FIG. 8B compares the particulate matter concentration at the inlet ofthe fluidized bed and a conventional RTO. It was found that theparticulate matter entering the fluidized bed was indeed representativeof the particulate entering the RTO, when calculated both on a poundsper hour (51.1 lb/hr versus 53.1 lb/hr) and a concentration (106.0mg/dscm versus 110.7 mg/dscm) basis.

To further investigate, the particulate control of the fluidized bed wascompared when used in conjunction with two different air pre-treatmentboxes. The first box contained a perforated plate, 100 mesh screen, anda pleated filter. The second box contained a perforated plate and twobaffles. The results are shown in FIG. 8C. Even without the 100 meshscreen and pleated filter, particulate matter was reduced between theuntreated exhaust stream and the outlet stream, indicating thatparticulate matter is reduced by the fluidized bed system. This is truewhen calculated on both a pounds per hour (48% without screen and filterversus 21.7% with screen and filter) and concentration (50.7% versus30.6%) basis. The particulate reduction was actually greater when usingthe perforated plate and two baffles as compared to with the 100 meshscreen and pleated filter. The specific reduction for each type ofparticulate studied (filterable, condensable, PM 2.5, and PM 10) can befound in Table 5, which extrapolates the average data to an air flowrate of 300,000 cfm. Overall, about 80 wt-% of the particles had adiameter of 1 μm or less.

TABLE 5 Particulate Inlet Avg. Outlet Avg. % (lb/hr) (lb/hr) ReductionMethod 5 (filterable only) 107 70 35% Method 202 (condensable) 42 33 21%Total filterable + 149 103 31% condensable PM 2.5 filterable + 49 35 29%condensable PM 10 filterable + 92 50 45% condensable

It was theorized that the fluidized beads acted as a dry scrubber toremove some of the particulate matter from the exhaust stream (whichalso formed the yellow/brown coating inside the air pre-treatment box).Thus, the desorption of this material was studied to determine whetherit could be desorbed along with terpenes in the desorber at a desorptiontemperature of 572° F. As shown in FIG. 8D, the thermal gravimetricanalysis of gum turpentine applied to carbon beads indicated that themajority of the organic material could be desorbed within 20 minutes at572° F., well within a desorber's design specifications for time andtemperature of 55 minutes at 572° F. Thus, it is expected that if thebeads adsorb this yellow/brown coating, it would be desorbed in thedesorber and be combined with a condensed turpentine product. However,inorganic material is never thermally desorbed and it is theorized itcan be recirculated with the beads back to the fluidized bed andexhausted out the top of the bed or circulated to a small particulatecontrol device for collection and disposal. Indeed, analysis of thecondensate showed that it contained fatty acids (hexadecanoic acid(C16:0) and octadecanoic acid (C18:0)) and rosins, which can be found inPM 2.5 (PM 2.5 includes both condensable and filterable particulatematter).

Additionally, the long term effects of particulates were studied over 2weeks of run time using an air pre-treatment box with a perforated plateand two baffles. After 2 weeks, the plate, baffles, fluidized bed, andairflow adjusters were all coated with a thin layer of yellow/brownmaterial. The elements in the pre-treatment box also had visibleparticles embedded in the layer of yellow/brown material.

Thus, this Example shows that the particulate going into the fluidizedbed is representative of the particulate going into a conventional RTO,indicating that these pilot trials can be used to predict the impact onparticulate matter. The fluidized bed was found to reduce particulateemissions by about 30% to 50%.

Additionally, it was observed that the fluidized beads in the bed removethe yellow/brown condensable organic material that typically forms ayellow/brown coating from the dryer exhaust, and it was theorized thatthey acted as a dry scrubber to do so. This condensable organic materialcan be desorbed in the desorber within the normal desorbertime/temperature design specification of 55 minutes at 572° F. and willbecome part of the resulting condensate. For PM 2.5, the condensablefraction is often the predominant fraction made up of rosin “smoke,”fatty acids, and breakdown products from cellulose and lignin. The airpre-treatment box with a perforated plate and two baffles, which is arelatively simple design, more effectively reduced particulate emissionsthan the box with a perforated plate, 100 mesh screen, and pleatedfilter.

Example 4: Terpene Yield from Beads

As described in Example 3, the conditions of desorption can affect theresulting composition of the terpenes recovered. Thus, in this Example,the desorption of terpenes from activated carbon beads was studied,while monitoring the composition of the desorbed materials.

The beads studied in this Example had previously undergone adsorptionwith an exhaust stream from a wood drying process as described inExample 3.

Beads that were saturated with terpenes (100.4 g) from a wood dryingprocess were placed in custom made glass desorption chamber with glassfrit (1.4 L volume). The chamber was equipped with a heating mantle (seeFIG. 9 ). The apparatus was heated slowly from room temperature (25° C.)to 190° C. over the course of 240 min. When temperature in the chamberreached 190° C., water began to condense (residual water from beads isdesorbed first), followed by condensation of the terpene stream. In aDean-Stark trap, a bi-phasic system was observed, with a bottom layer ofwater and a top layer of terpenes). Thereafter, the temperature wasmaintained within 10° C. and samples were collected at 4 intervals over115 minutes. The first and second samples included some water whereasthe third and fourth samples contained only organic phase. The organicphase was analyzed by GC/MS and results are summarized in Table 6 andFIG. 10 .

TABLE 6 Temp. Elapsed Terpene (° C.) Time (min) α-Pinene Campheneβ-Pinene p-Cymene Limonene Recovery  194¹ 10 6.8 0.4 2.1 0.1 0.3 9.7 19825 63.2 4.2 15.2 1.1 3.4 87.0 194 55 66.3 6.3 13.2 2.1 6.0 93.9 197 11554.0 8.8 7.6 3.8 9.8 83.9 ¹It took 240 min to heat-up the system from25° C. to 194° C. ^(2.) Recovery applies only to analytes that wereionized and detected by GC-MS.

As shown in Table 6 and FIG. 10 , as time elapsed, the relative amountof alpha-pinene and beta-pinene decreased relative to dipentene (e.g.,d-limonene) and camphene. The weight of the beads after desorption was92.8 g, indicating that 7.6 g of terpenes were recovered from thesaturated beads.

Room Temperature Liquid-Liquid Extraction

Adsorbed beads were extracted at room temperature using a mixture of thesolvents hexane, ethyl acetate, and acetonitrile at room temperature.The resulting solvent extracts were analyzed for terpene content. Theterpene content analyses were normalized based on the total amount ofterpenes and compared to thermally desorbed terpenes recovered by theDean-Stark analyses. The results of liquid-liquid extraction are shownin Table 7.

TABLE 7 Component Liquid Extraction % Alpha-Pinene 51 Camphene(Fenchene) 7 Beta-Pinene 25 Limonene 7 p-Cymene 5 Alpha-Terpineol 2p-Allylanisole 2

These data show that when terpenes were extracted with liquid at roomtemperature, there was a much larger percentage of alpha-pinene andbeta-pinene recovered. Additionally, this Example demonstrates thatterpenes can be recovered with organic solvents at room temperature.

Example 5: Sulfur Content of Terpene Recovery

To demonstrate an advantage of the presently disclosed terpene streams,this Example compares the composition of a terpene stream in accordancewith the present disclosure with the composition of a crude sulfateturpentine (CST) stream, which is commonly used as a source of terpenesand obtained from wood pulp digestion.

The crude sulfate turpentine stream of this Example represents theaverage composition of 11 crude sulfate turpentine streams fromdifferent sources. Table 8 provides a comparison of the sulfur andterpene content of the two streams.

TABLE 8 Crude Sulfate Recovered Terpenes Component Turpentine fromFluidized Bed Total Sulfur (ppm) 11,295 — DMTS (ppm) 68 — Alpha-Pinene(wt-%) 59.34%  63.2% Camphene (wt-%) 1.14%  4.2% Beta-Pinene (wt-%)23.62%  15.2% Myrcene (wt-%) 1.29% — Terpinolene (wt-%) 0.54% —Alpha-Terpineol (wt-%) 0.87% — Cis-Anethole (wt-%) 0.19% —Trans-Anethole (wt-%) 0.65% — Caryophyellenes (wt-%) 1.20% — Limonene(wt-%) 3.76%  3.4% Beta-Phellanderene (wt-%) 2.24% — Methyl Chavicol(wt-%) 0.76% —

As shown in Table 8, in contrast to crude sulfate turpentine, terpenesrecovered in accordance with the presently disclosed subject matter donot include sulfur-containing compounds (total sulfur and dimethyltrisulfide (DMTS)). Additionally, their alpha-pinene and beta-pinenecontent is similar to that of crude sulfate turpentine. Thus, theserecovered terpenes can be a sulfur-free alternative to crude sulfateturpentine, making them more valuable for many applications.

Example 6: Calculated Sorbent Reactivation via Side Stream Reactivator

This Example calculates and simulates the effect of continuous sidestream reactivation of carbon beads on sorbent apparent density over a21-day period. Such a calculation helps to determine the amount ofsorbent (i.e., carbon beads) that must be reactivated in order tomaintain a particular, desired sorbent apparent density. The ability tomaintain said sorbent apparent density is a primary predictor ofemissions reduction efficiency.

To calculate the effect of a side stream reactivator that continuouslyadds reactivated sorbent to maintain apparent density, each calculationbegins with spent carbon beads having an apparent density of 0.81 g/mL.It is assumed that each day, reactivated or fresh carbon beads increasewhen exposed to process air and subsequently desorbed by an apparentdensity of 0.01 g/mL. On this basis, five calculations are conducted todemonstrate the effect of 0.1%, 0.5%, 2%, 3%, and 6% reactivation perday based on a daily use of 10,000 lbs. of carbon beads. For example, a6% reactivation means 6% of 10,000 lbs. per day, or 600 lbs per day(which is 25 lbs/hr) reactivated.

Each of the five calculations begins with apparent density of 0.81 g/mL.For each day over a course of 21-days, the set percentage of reactivatedcarbon is mixed with existing sorbent. At the same time, all new andpartially spent sorbent that is adsorbed in the adsorber increases by0.01 g/mL per day to a maximum of 0.81 g/mL according to data collectedin FIG. 11A. FIG. 11B displays the calculated change in the apparentdensity of the sorbent beads over 21 days, based on the percentage ofreactivated carbon that is introduced.

It is desired to maintain sorbent apparent density at or approximately0.78 g/mL. Based on the calculated effect of side stream reactivation,about 2% reactivation of sorbent based on a 10,000 lb daily consumptionis sufficient to maintain this 0.78 g/mL apparent density. Lowerapparent density provides for improved percent reduction efficiency by ahigher percentage of reactivated sorbent (e.g., carbon), whereas higherapparent density provides for higher terpene yield, less use of energy,and less generated CO₂ by a lower percentage of reactivated sorbent(e.g., carbon).

Example 7: Emissions Control Via Side Stream Reactivation

This Example describes a pilot scale testing of the effect of continuousside stream reactivation of carbon beads in maintaining a certainsorbent apparent density, and accordingly, the ability to controlemissions from a process exhaust stream via a fluidized bed adsorber, ascontemplated by the presently disclosed methods and systems. ThisExample provided the introduction of fresh sorbent for a predeterminedamount of time into systems of the present disclosure to test the effectof continuous side stream reactivation. Specifically, this pilot scaletesting was conducted to determine the amount of new or reactivatedsorbent needed to consistently achieve over 90% reduction efficiency ofemissions, such as volatile organic compounds (VOCs) and/or totalhydrocarbon content (THC). Additionally, the effect of other equipmentoperating parameters was studied. The overall process flow of the systemin this Example is generally captured by FIG. 1 , as described above.

Prior to and in preparation for this pilot scale testing, the adsorberwas cleaned using trisodium phosphate solution in accordance toprocedures or processes as presently disclosed and known to those ofordinary skill in the art. Heating was provided to the adsorber, hopper(i.e., adsorber hopper), and associated piping to minimize possiblewater condensation and coalescence of organics.

New carbon beads were added in various but predetermined amounts overset increments of time (e.g., every 1-5 minutes) to simulate acontinuous side stream reactivation of the sorbent. The impacts ofadding new carbon, and thus of determining the effect of continuous sidestream reactivation as presently disclosed, were assessed based on thetime needed to observe reduction of emissions at the adsorber (e.g.,less than about 60 minutes) and a downstream desorber (e.g., betweenabout 5-10 hours). Side stream reactivation amount was adjusted in orderto maintain apparent densities ranging from about 0.78 g/mL to about0.80 g/mL, and subsequently, to achieve the necessary reductionefficiency on emissions of at least 90% from the process exhaust stream.

Operating conditions of this pilot scale testing are summarized in Table9 below. Sorbent beads from the adsorber spent about 60 minutes, with arange of between about 30-70 minutes, in the heated section of thedesorber.

TABLE 9 Condition Target Range Process Exhaust Air at Adsorber 300 cfm250-325 cfm Inlet Adsorber Differential Pressure 3.2-3.3 inches 2.5-4.5inches of H₂O of H₂O Hopper Temperature 180° F. 100-200° F. AdsorberMiddle and Upper 90-115° F. 90-115° F. Trays Sorbent Carbon BeadTransfer 48 lb/hr 40-85 lb/hr Rate from Desorber to Adsorber DesorberAverage Temperature 400° F. (or 370-470° F. 390-420° F.) CondenserChiller Temperature 45° F. 40-50° F. Condenser Chiller Pressure 43 psi41-45 psi Airlift Fan Pressure (Adsorber 20 inches of 18-22 inches andDesorber) H₂O of H₂O Nitrogen Makeup Pressure 35-45 30-50 NitrogenRecirculation Rate 8.5-9.1 cfm 8-10 cfm Nitrogen Blower Outlet Pressure29-32 inches 28-34 inches of H₂O of H₂O Apparent Density of Spent 0.81g/mL 0.81 g/mL Sorbent Apparent Density of Mixed (specific to 0.78-0.81Spent/New Sorbent test run) g/mL

After a baseline run to startup and acclimate the overall system, fourtest runs were conducted with the parameters specified in the tablebelow. For each run, an orifice was used at the inlet of the adsorber tomaintain the bead transfer rate from the desorber at about 48 lb/hr (orabout 21.8 kg/hr). The percentage of carbon beads as depicted in Table10 was calculated based on the 48 lb/hr sorbent bead transfer rate.

TABLE 10 Total Sorbent Sorbent Addition Location Where Apparent PercentAdded Rate New Sorbent Density Sorbent Run # [g] [g/min] Added [g/mL]Added Baseline 0 n/a n/a 0.81  0% A-1 1,473 49.1 Adsorber Top Tray 0.78012% A-2 1,473 44.6 Desorber Eductor 0.780 12% A-3 390 13.0 DesorberEductor 0.803 3.5%  A-4 552 8.7 Desorber Eductor 0.805 2.5% 

In Run A-1, new sorbent was introduced to the adsorber top tray byadding carbon beads approximately once per minute to the top adsorbertray via a pipe with double block and bleed valves at the top of theadsorber. In Run A-2, Run A-3, and Run A-4, new sorbent was introducedto the desorber eductor by introducing into the airstream between thedesorber educator and the desorber separator pot via a pipe and siteglass with double block and bleed valves.

Emission measurements, particularly VOCs and THC, were continuouslyrouted to flame ionization detection (FID) from both at the adsorberinlet and at the adsorber outlet. Analysis via flame ionizationdetection (FID) method was conducted by a certified third-party stacktesting company to determine the effectiveness on emission control ofthe overall system. Moreover, these emissions results were compared tothe amount of new carbon beads continuously added during this pilotscale testing (which demonstrated the function of a side streamreactivator) in order to determine an optimal apparent density range andthe percentage of sorbent that would need to be reactivated to maintainat least 90% reduction efficiency.

FIG. 12A shows the percent reduction efficiency as it varied with eachof four runs. In three of the four runs, a reduction efficiency of 100%was achieved, and in all instances, a reduction efficiency of 90% wasachieved when the apparent density of sorbent was maintained at about0.78 g/mL to about 0.805 g/mL. The average reduction efficiency achievedacross all four runs was about 98%.

Correspondingly, FIG. 12B shows the measurement of total hydrocarboncontent (THC) at the inlet of the adsorber compared to the outlet of theadsorber. As can be seen, as reduction efficiency increases due to theside stream reactivation of carbon beads in FIG. 12A, the THC at theadsorber outlet decreases nearly to zero, confirming the ability of thepilot system to attain about 100% reduction efficiency.

Based on the model in FIG. 11B, it is estimated that about 2%reactivation of sorbent per day is needed to maintain a consistentreduction efficiency of emissions at >90%. However, the full commercialsystem is designed to accommodate the capability to reactivate up to 6%sorbent per day on the basis of 10,000 lb. of sorbent (i.e., 600 lb/dayor about 25 lb/hr).

In addition to determining the amount of side stream reactivation ofsorbent to maintain a reduction efficiency of at least >90%, studieswere conducted to determine the effectiveness of a condenser coupled tothe desorber and the impact of adsorber differential pressure onemission control. FIG. 13 shows the total hydrocarbon content of themixed nitrogen and emissions stream exiting the condenser going back tothe desorber compared to the chiller temperature providing cooling tothe condenser. The apparent density was 0.81 g/mL during testing. As canbe noted in FIG. 13 , when the chiller temperature is cooler, e.g., atabout 40° F., the THC of the condenser outlet stream is correspondinglylower. By contrast, when the chiller temperature is closer to 50° F.,there is an upward tick in THC of the condenser outlet stream. ThisExample demonstrates that operating the chiller, and therefore thecondenser, at lower temperature improves condenser effectiveness bycondensing more THC content. Additionally, by operating the chiller atlower temperatures, terpene yield from the desorber can be collected andmaximized.

Adsorber differential pressure was also measured as compared to THC atthe adsorber inlet versus outlet, as well as adsorber emissions control.The apparent density was 0.81 g/mL during testing. FIG. 14A depictsvarious adsorber differential pressures (from about 2.5 inches of waterto about 3.8 inches of water) in comparison to the amount of THC in ppmat the adsorber inlet and outlet. As can be seen, where the adsorberoperates with a larger differential pressure, such as at or above 3.4inches of water, is the outlet THC content is higher than when theadsorber differential pressure is at or below 3.3 inches of water. FIG.14B confirmed this finding, as between about 2.4 inches of water toabout 3.2 inches of water shows an average reduction efficiency, withoutmodeling side stream reactivation, of about 62% to about 70%. However,when adsorber differential pressure is increased to about 3.4 inches ofwater, reduction efficiency drops to about 55% to about 60%.Accordingly, in certain embodiments, the adsorber operates such that itsdifferential pressure is maintained between about 2.5 inches of water toabout 3.3 inches of water.

It was also noted that some subsequent terpene yield was collected fromthe desorber of the pilot testing system. The amount of terpenecollected in this Example as scaled to anticipated commercial value isapproximately 50,000 gallons per year.

Example 8: Emissions Control via Side Stream Reactivation andComprehensive Testing

This Example was conducted subsequent to Example 7 above to confirm thereduction efficiency results achieved via continuous side streamreactivation of sorbent. Additionally, comprehensive stack testing wasconducted for environmental permitting regulations. In particular, thecomprehensive stack testing also measured the amount of VOCs by FID,particulate matter, HAPs, SO₂, methane (CH₄), nitrogen oxides (NO_(x)),oxygen (O₂), and carbon monoxide (CO). An apparent density target wasselected to achieve >90% reduction efficiency during comprehensive stacktesting.

Prior to testing, the adsorber of the present Example was cleaned.During cleaning, the amount of pH of water rinses were monitored. Thefollowing table illustrates the adsorber cleaning process. Additionally,airlift systems of the pilot testing system, shown in FIG. 1 , forinstance, the adsorber eductor and desorber bead transfer line, weredried out to remove water and any organics coalescing.

TABLE 11 Average Solution Step Cleaning Process PH 1 First rinse withapproximately 4 gallons of water. 7.23 2 Apply cleaning solution, e.g.,4 liters (about 1 gallon) of 11.95 10% trisodium phosphate. 3 Draincleaning solution and drain organics from adsorber. 12.01 4 Second rinsewith approximately 5 gallons of water. 10.34 5 Third rinse withapproximately 5 gallons of water. 8.81 6 Fourth rinse with approximately5 gallons of water 8.30

New carbon beads were added in various but predetermined amounts overset increments of time (e.g., every 1-5 minutes) to simulate acontinuous side stream reactivation of the sorbent. The impacts ofadding new carbon, and thus of determining the effect of continuous sidestream reactivation as presently disclosed, were assessed based on thetime needed to observe reduction of emissions at the adsorber (e.g.,less than about 60 minutes) and a downstream desorber (e.g., betweenabout 5-10 hours). Side stream reactivation was adjusted in order tomaintain apparent densities ranging from about 0.760 g/mL to about 0.80g/mL, and subsequently, to achieve the necessary reduction efficiency onemissions of at least 90% from the process exhaust stream.

The trial testing of this Example was conducted over the course of twodays, i.e., in two parts. In the first part, this Example aimed toconfirm the side stream reactivation conducted in Example 7 above. Aftera baseline run to startup and acclimate the overall system, two runswere conducted with the parameters specified in the table below. Foreach run, an orifice was used at the inlet of the adsorber to maintain adesired bead transfer rate to the desorber at about 38 lb/hr (or about17.2 kg/hr) or at about 44 lb/hr (or about 20.0 kg/hr). The percentageof carbon beads as depicted in Table 12 was calculated based on the 1b/hr sorbent bead transfer rate.

TABLE 12 Total Sorbent Bead Location Apparent Percent Sorbent AdditionTransfer Rate Where New Density Sorbent Run # Added [g] Rate [g/min][lb/hr] Sorbent Added [g/mL] Added Baseline 0 n/a n/a n/a 0.81  0% B-11,179.3 39.3 38 (17.2 kg/hr) Desorber Eductor 0.785 12% B-2 2,116.8 10644 (20.0 kg/hr) Desorber Eductor 0.760 24%

In Run B-1, new carbon sorbent beads were added once per minute over 30minutes. In Run B-2, new carbon was added once per minute over 20minutes. In both Run B-1 and B-2, new sorbent was introduced desorbereductor directly by introducing into the airstream between the desorbereductor and the desorber separator pot via a pipe and site glass withdouble block and bleed valves.

Emission measurements, particularly VOCs, were continuously routed toflame ionization detection (FID) from both at the adsorber inlet and atthe adsorber outlet. Analysis via flame ionization detection (FID)method was conducted by a certified third-party stack testing company todetermine the effectiveness on emission control of the overall system.Moreover, these emissions results were compared to the amount of newcarbon beads continuously added during this pilot scale testing (whichdemonstrated the function of a side stream reactivator) in order todetermine an optimal apparent density range and the percentage ofsorbent that would need to be reactivated to maintain at least 90%reduction efficiency.

FIG. 15 shows the reduction efficiency as it varied with each of the tworuns in this Example. Run B-2 achieved a reduction efficiency of 100%,and in both instances, a reduction efficiency of at least 90% wasachieved when the apparent density of sorbent was maintained at about0.760 g/mL to about 0.785 g/mL.

Further, as observed from FIG. 15 , in the first pilot testing part ofExample 8, the THC at the adsorber outlet was drastically lower than theamount of THC at the adsorber inlet. This confirms the side streamreactivation of Example 7, as well as this Example, can obtain >90%reduction efficiency of emissions from a process exhaust stream.

Operating conditions during the second part of pilot scale comprehensivetesting of this Example are summarized in Table 13 below. Sorbent beadsfrom the adsorber spent about 60 minutes, with a range of between about30-70 minutes, in the heated section of the desorber.

TABLE 13 Condition Target Range Process Exhaust Air at Adsorber 300 cfm250-325 cfm Inlet Adsorber Differential Pressure 3.2 inches of 2.5-4.5inches H₂O of H₂O Hopper Temperature 180° F. 145-170° F. Adsorber Middleand Upper 90-115° F. 90-115° F. Trays Sorbent Carbon Bead Transfer 34lb/hr 30-50 lb/hr Rate Desorber Average Temperature 400° F. 360-470° F.Condenser Chiller Temperature 45° F. 40-50° F. Condenser ChillerPressure 43 psi 41-45 psi Airlift Fan Pressure (Adsorber 20 inches of18-22 inches and Desorber) H₂O of H₂O Nitrogen Makeup Pressure 37-43inches 30-50 inches of H₂O of H₂O Nitrogen Recirculation Rate 9 cfm 7-11cfm Nitrogen Blower Outlet Pressure 28-32 inches 26-34 inches of H₂O ofH₂O Apparent Density of Spent 0.81-0.813 0.81-0.813 Sorbent g/mL g/mLApparent Density of Mixed (specific to 0.78-0.81 Spent/New Sorbent testrun) g/mL

After a baseline run to startup and acclimate the overall system forcomprehensive testing, two test runs were conducted with the parametersspecified in the table below. For each run, the bead transfer rate goingto and through the adsorber was about 34 lb/hr (or about 15.4 kg/hr).Addition of new sorbent in this second part comprehensive testing wasabout 43 grams per minute.

TABLE 14 Total Sorbent Bead Location Where Apparent Percent SorbentAddition Transfer New Sorbent Density Sorbent Run # Added [g] Rate[g/min] Rate [lb/hr] Added [g/mL] Added Baseline 0 n/a n/a n/a 0.81  0%C-1 2,585.5 43.1 34 Desorber Eductor 0.780 14% C-2 2,585.5 43.1 34Desorber Eductor 0.780 14%

In the baseline and startup run for comprehensive testing in FIG. 16A,side stream reactivation is first performed for the overall system. Ascan be seen, around a run time of about 12:35, the reduction efficiencybegins to increase from about 60% toward >90% as new carbon beads werebeing added. Simultaneously, the adsorber outlet THC begins to decreaseas adsorption of emissions begins to take place in the fluidized bedadsorber. Prior to the three comprehensive testing runs, the system wasfirst brought up to environmental regulations of achieving >90%reduction efficiency.

Two comprehensive runs, C-1 and C-2 were conducted in the second part ofthis Example for environmental permit submission. For each comprehensiverun, the sorbent apparent density was maintained at about 0.78 g/mL viaside stream reactivation. Comprehensive run C-1 displayed in FIG. 16Bachieved and maintained a target of >90% reduction efficiency over orthroughout approximately 1 hour. Comprehensive run C-2 displayed in FIG.16C also achieved and maintained a target of >90% reduction efficiencyover or throughout approximately 1 hour.

Based on the model in FIG. 11B, it is estimated that about 2%reactivation of sorbent per day is needed to maintain a consistentreduction efficiency of emissions at >90%. However, the full commercialsystem is designed to accommodate the capability to reactivate up to 6%sorbent per day on the basis of 10,000 lb. of sorbent (i.e., 600 lb/dayor about 25 lb/hr).

Some subsequent terpene yield was also collected from the desorber ofthe pilot testing system in Example 9.

Example 9: Terpene Recovery

In this Example, operational conditions were adjusted in order tomaximize terpene yield recovery from the desorber as contemplated by thepresent disclosure. Table 15 below provides the operational settings forseveral experimental runs.

TABLE 15 Condition Target Range Process Exhaust Air at Adsorber 300 cfm250-325 cfm Inlet Adsorber Differential Pressure 3.2 inches of 2.5-4.5inches H₂O of H₂O Hopper Temperature 180° F. 115-144° F. Adsorber MiddleTrays 155° F. 137-158° F. Adsorber Upper Trays 130° F. 126-142° F.Adsorber & Desorber Eductors 155° F. — Sorbent Carbon Bead Transfer60-80 lb/hr 50-90 lb/hr Rate Desorber Average Temperature 400° F.,320-530° F. 410° F., 430° F. Condenser Chiller Temperature 45° F.,40-50° F., 34° F. 32-39° F. Condenser Chiller Pressure 43 psi 41-45 psiAirlift Fan Pressure (Adsorber 20 inches of 18-22 inches and Desorber)H₂O of H₂O Nitrogen Makeup Pressure 28-42 inches 25-45 inches of H₂O ofH₂O Nitrogen Recirculation Rate 8-9 cfm 8-12 cfm Nitrogen Blower OutletPressure 30-32 inches of 28-34 inches H₂O, 35-42 of H₂O, 30-45 inches ofH₂O inches of H₂O Apparent Density of Spent 0.81 g/mL — Sorbent ApparentDensity of Mixed 0.780 g/mL — Spent/New Sorbent

A system as described in FIG. 1 was used for pilot operation to recoverterpenes from process exhaust streams. In system, from a two-passcondenser water and terpenes samples were measured via a graduatedcylinder. Such a condenser also was equipped with two sight glasses toobserve condensed materials exiting the two-pass condenser. Unlesssamples were being collected, condensate was directed via a tube to a 10gallon drum for collection and storage.

Several runs were conducted over the course of several months in acontinuous process. It was observed that terpenes were not immediate toform, and the system, including sorbent beads, required a certain amountof warm-up time. It is theorized that the sorbent beads must cyclethrough several adsorption and desorption iterations before any terpenesthat are formed or existing on the sorbent can be desorbed andcollected. Further, it is theorized that the sorbent beads need to reachterpenes equilibrium prior to desorption of terpenes from the sorbentbeads. Terpenes equilibrium is a point at which terpenes are equallyadsorbed and then desorbed. Prior to terpenes equilibrium, terpenes arepreferably adsorbed but not desorbed (i.e., released). Terpenesadsorption onto the sorbent is preferred when the sorbent is new (i.e.,exothermic). Further, terpene loading onto the sorbent must reach aweight by weight loading ratio that provides the equilibrium workingcapacity at desorber temperature. The equilibrium point changes based onthe temperature of the desorber temperature.

An experimental run was conducted to assess the effect of time andtemperature on terpenes yields based on the following steps. The targetapparent density was 0.780 g/mL, and new carbon beads were adjustedtwice per day.

TABLE 16 Chiller Recirculation Step Duration Run Details TemperatureFlow 1 12 hr Baseline. Desorber at 400° F. 40-50° F. 8.5 cfm Beadtransfer rate at 60-80 lb/hr. 2 14 hr Baseline. Adjust chiller to 35° F.8.5 cfm 34° F. 3  5 hr Baseline. Increase N₂ flow. 35° F. 12.0 cfm  4 20hr Repeat baseline. Desorber at 34° F. 9.0 cfm 400° F. 5 15 hr Adjustdesorber to 410° F. 34° F. 8.5 cfm 6  1 hr Temperature excursion up to34° F. 8.5 cfm 437° F. 7 12 hr Adjust desorber to 430° F. 34° F. 8.5 cfm8 22 hr Adjust desorber to 400° F. 34° F. 8.0 cfm 9  9 hr Shutdown 34°F. 8.0 cfm

Observation and measurements were taken at the two condenser sightglasses. Water and terpenes were collected via a graduated cylinder.Terpene production was calculated for a full commercial scale system,given that the pilot system is about 1/1,000 the size, and given that afully commercial plant is anticipated to operate approximate 5,815 hoursper year.

FIG. 17 shows the effect of time and sorbent temperature on carbontemperature, percent reduction efficiency and apparent density.

FIG. 18A shows the terpenes yield with time based on the above-specifiedrun. As can be seen in FIG. 18A, when the desorber is operating at about400-410° F., there is consistent terpene yield of about 40,000 to about70,000 gallons per year per condenser pass or about 80,000 to about100,000 total gallons per year. However, when the desorber temperatureis increased to about >430° F., terpene yield across both sight glass #1and sight glass #2 decreased.

FIG. 18B also provides another instance of terpene yield for anexperimental run conducted earlier in time than the trial runcorresponding to FIG. 18A. By totaling the amount collected at sightglass #1 with the amount collected at sight glass #2, it was possible toextrapolate the pilot runs of terpene yields for annualized terpeneyield of a full scale commercial system. This full commercial system andterpenes yields is shown in FIG. 19 .

Various experimental runs were further analyzed for specific terpeneyields. In a first series, the breakdown between alpha-pinene orbeta-pinene versus other terpene products and fatty acids is shown inFIGS. 20A, 20B, and 20C where the desorber is respectively operating atabout 425° F., between about 450-600° F., and at about 500° F. Together,FIGS. 20A, 20B, and 20C indicate that during initial desorption, therewas lower alpha-pinene and beta-pinene content. However, with laterdesorption, more alpha- and beta-pinene was present. It is theorizedthat sorbent beads must undergo several iterations of adsorbing anddesorbing before reaching terpenes equilibrium where terpenes will beginto desorb. During this time, it is theorized that exposure to repeatedheating cycles can cause thermal deterioration.

FIG. 21 represents a second series of terpene analysis. Again, there waslower alpha- and beta-pinene content during initial desorption, but thealpha- and beta-pinene content increased with later desorption.

FIG. 22 represents terpenes analysis corresponding to a third series asdiscussed above in Table 16. Here, the pilot system of the presentdisclosure had a period of time to enter later desorption. FIG. 22 showsalpha-pinene content ranging from approximately 31% to about 35% andbeta-pinene content range from approximately 13% to about 17%. Lowervalue terpenes, such as o-cymene and camphene are a smaller percentageof the total terpene yield as compared to the first series in FIGS. 20A,20B, and 20C or the second series in FIG. 21 .

In addition to terpenes, some carboxylic acid salts were also collectedand identified. IR and x-ray analysis indicated collected solid materialcontained a primary alcohol functional group with small C—H bands.

Based on terpene yields produced, this Example suggests that operatingthe desorber at a temperature range of about 390° F. to about 430° F.provides desirable terpene desorption. Further, alpha-pinene and/orbeta-pinene yield is higher after an initial terpene equilibrium isreached in the desorber. This suggests that longer term operation canyield terpene solutions with approximately 50% or more alpha-pineneand/or beta-pinene.

Additionally, operation measurements were taken of the estimated %reduction efficiency, sorbent (i.e., carbon bead) temperature in adownstream desorber, and sorbent apparent density with time. Side streamreactivation was not performed in these measurements. A plot of theoperational measurements is provided at FIG. 23 .

As can be seen in FIG. 23 , sorbent apparent density increases withtime. Decreases in the apparent density curve indicate when spentsorbent was replaced with fresh carbon, which simulates side streamreactivation. As apparent density increases and approaches about 0.8g/mL, there was generally a corresponding decrease in % reductionefficiency. This supports the theory that as apparent density increases,and sorbent beads begin to adsorb less emissions materials andparticulates, the ability for emissions control decreases.

Sorbent temperature was varied between about 300° F. to about 600° F. Athigher temperatures of about 600° F., it was discovered that no terpeneswere desorbed in a downstream desorber. This supports the theory thathigher sorbet temperatures of about 600° F. are not required to desorbspent sorbent and simultaneously recover terpene products. It wastheorized that higher desorber temperatures of 600° F. chemical alterwould-be terpene products into other non-terpene compounds, causingpolymerization and/or thermal degradation. Instead, the desorber can beoperated at lower temperatures around 400° F. to desorb spent carbonbeads while achieving terpene products from desorbed material.

In addition to the various embodiments depicted and claimed, thedisclosed subject matter is also directed to other embodiments havingother combinations of the features disclosed and claimed herein. Assuch, the particular features presented herein can be combined with eachother in other manners within the scope of the disclosed subject mattersuch that the disclosed subject matter includes any suitable combinationof the features disclosed herein. The foregoing description of specificembodiments of the disclosed subject matter has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the disclosed subject matter to those embodimentsdisclosed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the systems and methods ofthe disclosed subject matter without departing from the spirit or scopeof the disclosed subject matter. Thus, it is intended that the disclosedsubject matter include modifications and variations that are within thescope of the appended claims and their equivalents.

Various patents and patent applications are cited herein, the contentsof which are hereby incorporated by reference herein in theirentireties.

What is claimed is:
 1. A method for recovering terpenes derived from awood drying process, comprising: providing a process exhaust stream froma wood drying process, the process exhaust stream comprising one or moreterpenes; flowing the process exhaust stream through a fluidized bed ofsorbent within at least one adsorber, the sorbent configured to capturethe one or more terpenes from the process exhaust stream at a firsttemperature; flowing the sorbent having the captured terpenes through atleast one desorber; heating the fluidized sorbent within the at leastone desorber to a second temperature sufficient to release the capturedterpenes from the sorbent to provide a gaseous stream comprising thereleased terpenes; and collecting the terpenes from the gaseous streamexiting the at least one desorber, wherein the gaseous stream exitingthe at least one desorber comprises at least 90% of the terpenes fromthe process exhaust stream derived from the wood drying process, flowinga side stream of the fluidized bed from the at least one desorber to areactivator operated at a third temperature sufficient to thermallyreactivate the sorbent; and returning the reactivated sorbent to the atleast one adsorber.
 2. The method of claim 1, wherein the secondtemperature is greater than about 302° F. and less than about 450° F. 3.The method of claim 2, wherein the gaseous stream exiting the at leastone desorber comprises alpha-pinene, beta-pinene, or a combinationthereof.
 4. The method of claim 3, wherein the gaseous stream exitingthe at least one desorber comprises from about 1 wt-% to about 20 wt-%alpha-pinene and from 0 wt-% to about 20 wt-% beta-pinene.
 5. The methodof claim 1, further comprising maintaining the fluidized sorbent withinthe at least one desorber at the second temperature for about 30 minutesto less than about 2 hours.
 6. The method of claim 5, wherein thefluidized sorbent within the at least one desorber is maintained at thesecond temperature for about 30 minutes to about 1.5 hours.
 7. Themethod of claim 5, wherein the second temperature is less than about430° F.
 8. The method of claim 5, wherein the second temperature is fromabout 390° F. to about 420° F.
 9. The method of claim 1, wherein thegaseous stream exiting the at least one desorber comprises from about 50wt-% to about 97 wt-% of alpha-pinene and beta-pinene combined.
 10. Themethod of claim 1, wherein the gaseous stream exiting the at least onedesorber comprises alpha-pinene in an amount of from about 20 wt-% toabout 97 wt-%.
 11. The method of claim 1, wherein the gaseous streamexiting the at least one desorber comprises beta-pinene in an amount offrom about 5 wt-% to about 60 wt-%.
 12. The method of claim 1, whereinthe gaseous stream exiting the at least one desorber comprises from 0wt-% to about 20 wt-% of dipentene.
 13. The method of claim 1, whereinthe gaseous stream exiting the at least one desorber comprises from 0wt-% to about 15 wt-% of camphene.
 14. The method of claim 1, whereinthe gaseous stream exiting the at least one desorber is free of sulfur.15. The method of claim 1, wherein the gaseous stream exiting the atleast one desorber further comprises nitrogen, steam, or both.
 16. Themethod of claim 15, wherein the gaseous stream exiting the at least onedesorber comprises at least 95 wt-% nitrogen.
 17. The method of claim 1,wherein the gaseous stream exiting the at least one desorber furthercomprises a hazardous air pollutant selected from the group consistingof formaldehyde, methanol, phenol, acrolein, acetaldehyde,propionaldehyde, fatty acids, acetic acid, and combinations thereof. 18.The method of claim 1, wherein the sorbent comprises activated carbon.19. The method of claim 1, wherein the at least one desorber includesone or more access panels.
 20. The method of claim 1, wherein collectingthe terpenes from the gaseous stream exiting the at least one desorbercomprises condensing the terpenes through a cooling system.
 21. Themethod of claim 20, wherein the cooling system comprises a condenser.22. A method for recovering terpenes derived from a wood drying process,comprising: providing a process exhaust stream from a wood dryingprocess, the process exhaust stream comprising one or more terpenes;flowing the process exhaust stream through a fluidized bed of sorbentwithin at least one adsorber operated at a first temperature of about130° F. to about 220° F., the sorbent configured to capture the one ormore terpenes from the process exhaust stream at the first temperature;flowing the sorbent having the captured terpenes to at least onedesorber operated at a second temperature of about 302° F. to about 450°F. to release the captured terpenes from the sorbent to provide agaseous stream comprising the released terpenes; collecting the terpenesfrom the gaseous stream exiting the at least one desorber, wherein theterpenes include alpha-pinene, beta-pinene or both; flowing a sidestream of the fluidized bed from the at least one desorber to areactivator operated at a third temperature of about 1,000° F. to about1,600° F. to thermally reactivate the sorbent; and returning thereactivated sorbent to the at least one adsorber, wherein the gaseousstream exiting the at least one desorber comprises at least 90% of theterpenes from the process exhaust stream derived from the wood dryingprocess.
 23. The method of claim 22, wherein the at least one adsorberis directly linked to the at least one desorber.
 24. The method of claim22, wherein the process exhaust stream is derived from drying softwoodsand the terpines comprise alpha-pinene, beta-pinenes, or a combinationthereof.
 25. The method of claim 22, wherein the gaseous stream exitingthe at least one desorber comprises alpha-pinene in an amount of from 20wt-% to about 97 wt-%.
 26. The method of claim 22, further comprisingchemically treating the sorbent within the reactivator using steam,super critical carbon dioxide, caustic solution, or any combinationthereof.
 27. A method for recovering terpenes derived from a wood dryingprocess, comprising: contacting a process exhaust stream derived from awood drying process, the process exhaust stream comprising one or moreterpenes, with a sorbent at a first temperature, the sorbent configuredto capture the one or more terpenes from the process exhaust stream atthe first temperature; thermally treating the sorbent having thecaptured terpenes at a second temperature, the second temperaturesufficient to release the captured terpenes from the sorbent to providea gaseous stream comprising the released terpenes and treated sorbent;thermally reactivating a portion of the treated sorbent at a thirdtemperature sufficient to thermally reactivate the sorbent; combiningthe treated sorbent and the reactivated sorbent; contacting the combinedtreated sorbent and the reactivated sorbent with the process exhauststream derived from the wood drying process; and collecting the releasedterpenes from the gaseous stream, wherein the gaseous stream comprisesat least 90% of the terpenes from the process exhaust stream derivedfrom the wood drying process.
 28. The method of claim 27, wherein thefirst temperature is about 130° F. to about 220° F.
 29. The method ofclaim 27, wherein the second temperature is about 302° F. to about 450°F.
 30. The method of claim 27, wherein the third temperature is betweenabout 1,000° F. and about 1,600° F.
 31. The method of claim 27, whereinthe process exhaust stream is derived from drying softwoods.
 32. Themethod of claim 27, wherein the sorbent is fluidized within an adsorberwhile contacting the process exhaust stream.
 33. The method of claim 27,further comprising chemically treating the sorbent using steam, supercritical carbon dioxide, caustic solution, or any combination thereofwhile thermally reactivating the sorbent at the third temperature.